Tennessee Onions Casserole Recipe – Easy Comforting Cheesy Bake

Name: Tennessee Onions Casserole
Prep time: 10 min
Cook time: PT-490124H6M31S
Total time: PT-490124H6M31S
Cuisine: Southern
Ingredients: 3-4 large sweet onions (Vidalia or yellow, about 1.75 lbs), peeled and sliced into thick rounds; 2-3 tablespoons unsalted butter, melted; 1/2 teaspoon garlic powder; 1/2 teaspoon salt; 1/2 teaspoon black pepper; 1 cup shredded cheddar cheese; 1/2 cup shredded mozzarella cheese; 1/2 cup grated Parmesan cheese; 1 cup panko breadcrumbs; 2 tablespoons melted butter (for topping); 1 tablespoon chopped fresh parsley (optional); Dash of smoked paprika (optional); Chopped cooked bacon (optional); Pepper jack cheese (optional, swap for cheddar for heat)

Posted on November 28, 2025

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Comfort Food

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Let me tell you—the aroma of sweet, caramelized onions mingling with bubbling, golden cheese drifting from my oven is pure Tennessee comfort. The first time I made this Tennessee Onions Casserole, I honestly had no idea what I was in for. You know that magical moment when you open the oven and the kitchen fills with a rich, savory scent that promises warmth and nostalgia? That’s this casserole in a nutshell. It was one of those rainy Saturday afternoons (the kind where the sky just can’t make up its mind), and I found myself craving something both simple and soul-soothing.

Years ago, when I was knee-high to a grasshopper, my grandma used to whip up cheesy bakes with whatever she had on hand. She swore by the power of onions—said they were the backbone of Southern flavor. I stumbled onto this particular recipe while flipping through a dusty old church cookbook at a yard sale (I’ll admit, I’m a sucker for handwritten notes and dog-eared pages). The first bite took me straight back to Grandma’s kitchen, where laughter mingled with the scent of roasting onions and cheese.

My family couldn’t stop sneaking spoonfuls straight from the baking dish (I can’t blame them, really). Even my youngest, who claims to “hate onions,” was caught scraping up every last bit. There’s just something about the gooey cheese, the sweet onions, and the buttery crunch that gets everyone coming back for seconds. Honestly, this Tennessee Onions Casserole is dangerously easy and delivers pure, nostalgic comfort—the kind you want to bring to potlucks, serve as a sweet treat for your kids, or brighten up your Pinterest recipe board. After testing this recipe more times than I care to admit (in the name of research, of course), it’s become a staple for family gatherings, cozy dinners, and last-minute meal needs. It feels like a warm hug on a plate, and you’re absolutely going to want to bookmark this one for every season.

Why You’ll Love This Tennessee Onions Casserole Recipe

If you’ve ever craved a dish that’s equal parts easy, cheesy, and crowd-pleasing, this Tennessee Onions Casserole is your answer. I’ve made this recipe for everything from lazy Sunday suppers to packed holiday gatherings, and it never disappoints. Let’s face it—there’s comfort in knowing you can whip up something truly delicious without breaking a sweat or emptying your wallet. Here’s why it stands out:

Quick & Easy: Comes together in under 10 minutes of prep—great for busy weeknights or when you need a side dish in a hurry.
Simple Ingredients: No fancy grocery runs required. Most of these are pantry staples or easy finds in any supermarket.
Perfect for Any Occasion: From potlucks and holiday feasts to backyard barbecues, this casserole fits right in.
Crowd-Pleaser: I’ve served this to picky eaters and foodies alike, and it always gets those “Can I have the recipe?” requests.
Unbelievably Delicious: The combo of sweet onions, gooey cheese, and buttery crunch is next-level comfort food. Close your eyes after the first bite and you’ll see what I mean.

What makes this Tennessee Onions Casserole different? For starters, I use a blend of cheeses for richer flavor and smoother melt—none of that rubbery texture you get from just one type. The onions are sliced thick, which lets them soften and sweeten without turning mushy. I toss in a dash of garlic powder and a sprinkle of fresh herbs (just enough for a hint of complexity). It’s not just another cheesy bake—it’s the kind of casserole that feels homey, but with a little extra flair.

Honestly, this casserole is more than just food. It’s a memory-maker, a conversation starter, and the sort of dish that turns even a regular meal into something memorable. It’s comfort food reimagined—healthier, faster, and still packed with all that soul-soothing satisfaction. Whether you’re impressing guests or just treating yourself, the Tennessee Onions Casserole makes every bite count.

What Ingredients You Will Need

This Tennessee Onions Casserole recipe uses simple, wholesome ingredients to deliver bold flavor and that irresistible cheesy texture. Most of what you need is probably already sitting in your kitchen, and there’s plenty of room for easy swaps or additions. Here’s a breakdown of everything you’ll need:

For the Casserole Base:
- 3-4 large sweet onions (Vidalia or yellow work best, about 800g; peeled and sliced into thick rounds)
- 2-3 tbsp unsalted butter (30-45g; melted, adds richness and helps the onions caramelize)
- 1/2 tsp garlic powder (for a hint of savory depth—I like McCormick)
- Salt & black pepper to taste (about 1/2 tsp each; adjust as needed)
Cheese Layer:
- 1 cup shredded cheddar cheese (120g; sharp or mild, your choice—Cabot is my go-to for flavor)
- 1/2 cup shredded mozzarella cheese (60g; gives that gooey, stretchy melt—part-skim works fine)
- 1/2 cup grated Parmesan cheese (40g; adds salty umami and a crisp topping—try Kraft or freshly grated)
Topping:
- 1 cup panko breadcrumbs (50g; for extra crunch—regular or gluten-free both work)
- 2 tbsp melted butter (30g; helps the topping brown and adds flavor)
- 1 tbsp chopped fresh parsley (optional, for color and freshness)
Optional Add-Ins:
- Dash of smoked paprika (for a faint smoky kick)
- Chopped cooked bacon (for a hearty, Southern twist)
- Swap cheddar for pepper jack if you want a bit of heat

If you’re looking to make this gluten-free, simply swap the panko for your favorite gluten-free breadcrumbs. Dairy-free cheese substitutes melt fine, but the flavor will be a little different (Daiya is decent in this casserole). For a lighter version, use reduced-fat cheeses and skip the extra butter. In the summer, I sometimes toss in a few sliced fresh tomatoes with the onions—makes it bright and juicy.

Truly, the beauty of this Tennessee Onions Casserole is how flexible the ingredients are. Pick your favorite cheese blend, swap the breadcrumbs, or throw in an extra veggie here and there. It’s all about comfort, flavor, and making it your own.

Equipment Needed

You don’t need much to whip up this Tennessee Onions Casserole—which is a relief, honestly. Most of what you’ll need is probably in your kitchen already. Here’s what I use every time:

9×13-inch baking dish (or similar size; glass or ceramic is best for even browning)
Cutting board & sharp chef’s knife (for slicing onions—watch your fingers, those onions can get slippery!)
Mixing bowls (one large for tossing onions and cheese, another small for breadcrumbs and butter)
Measuring cups and spoons (accuracy counts, especially for cheese and spices)
Aluminum foil (for covering during part of the baking; keeps everything melty and moist)
Oven mitts (trust me, this casserole gets HOT)

If you don’t have a 9×13-inch dish, a deep pie plate or two smaller casserole dishes will work. I’ve used disposable foil pans for potlucks plenty of times—no shame in making cleanup easier! If you’re short on mixing bowls, clean out your salad spinner or use a big soup pot. For breadcrumbs, a food processor is handy, but honestly, smashing them up in a zip-top bag with a rolling pin does the trick.

After using my glass baking dish for years, I always give it a quick soak in warm water right after serving—makes cleaning much easier. For budget-friendly options, check out thrift stores (I scored my favorite casserole dish for $2). Just remember, whatever you use, the magic is in the layering and the bake.

Preparation Method

Preheat the Oven: Set your oven to 350°F (175°C). Give it a little time to really heat up so your casserole browns properly.
Prepare the Onions: Peel 3-4 large sweet onions (about 800g) and slice them into thick rounds—about 1/2 inch (1.3cm) each. If you go too thin, the onions will melt away and lose their texture. Place the slices in a large mixing bowl.
Season & Toss: Drizzle the onions with 2-3 tbsp melted butter (30-45g). Sprinkle over 1/2 tsp garlic powder, 1/2 tsp salt, and 1/2 tsp black pepper. Toss gently to coat each slice—your hands work best here. The onions should be glossy but not swimming in butter.
Layer the Onions: Arrange the seasoned onion slices in your 9×13-inch baking dish, overlapping slightly. Try to keep the layers even so everything cooks at the same rate. (If you’re using tomatoes or bacon, tuck them between the onions now.)
Add Cheese: Sprinkle 1 cup shredded cheddar (120g) evenly over the onions, followed by 1/2 cup mozzarella (60g) and 1/2 cup Parmesan (40g). Press down lightly so the cheese nestles between the onions.
Prepare the Topping: In a small bowl, combine 1 cup panko breadcrumbs (50g) with 2 tbsp melted butter (30g). Mix until the crumbs are evenly moistened. Stir in 1 tbsp chopped parsley if using.
Top the Casserole: Sprinkle the breadcrumb mixture evenly over the cheese. This is what gives you that golden, crunchy crust.
Bake Covered: Cover the dish loosely with aluminum foil. Bake for 25 minutes—this lets the onions soften and the cheese melt without the topping getting too brown.
Bake Uncovered: Remove the foil and bake for another 20-25 minutes, until the topping is golden brown and the casserole is bubbling around the edges. Keep an eye out—the smell will be irresistible by now!
Rest & Serve: Let the casserole rest for 10 minutes before serving. This helps everything set up and makes it easier to slice. The cheese should be gooey, the onions sweet and tender, and the topping crisp.

Troubleshooting Tips: If the onions seem dry before baking, drizzle with another tablespoon of melted butter. If the topping browns too quickly, tent with foil for the last 10 minutes. For a deeper flavor, use half smoked cheese or add a dash of paprika.

Sensory cues: The onions should soften but still hold shape, the cheese layer should be bubbling, and the top should be a crunchy, deep gold. If you hear a gentle sizzle when it comes out, you did it right! My personal tip: slice your onions ahead of time and keep them in the fridge—cuts down on tears and saves time when you’re ready to cook.

Cooking Tips & Techniques

Over the years, I’ve picked up a few tricks that make my Tennessee Onions Casserole turn out perfectly every time. Here’s what I’ve learned—sometimes the hard way!

Slice Onions Thick: Thin slices can turn mushy, especially with extended baking. Keep them at least 1/2-inch (1.3cm) thick for that sweet-tender bite.
Layer Evenly: Uneven layers can cause some onions to burn while others stay raw. I always arrange mine in a slightly overlapping pattern for even cooking.
Mix Cheeses: Using a blend of cheddar, mozzarella, and Parmesan gives you the best melt and flavor. I tried just cheddar once—too greasy and one-note.
Breadcrumbs Matter: Panko gives you a lighter, crunchier topping than regular breadcrumbs. If you only have regular, add a pinch of salt and a splash of olive oil.
Watch the Bake Time: My oven runs a little hot, so sometimes I have to check at the 20-minute mark. If the topping is browning too fast, I tent with foil (learned that after one too many burnt crusts).
Rest Before Serving: This is key! If you dig right in, the casserole can fall apart. The flavors settle and the texture firms up if you wait just 10 minutes.
Multitasking: Prep onions and cheese while the oven heats. You can even assemble the casserole ahead of time, then bake when ready.
Flavor Boosts: For extra depth, add a pinch of nutmeg or smoked paprika to the cheese layer. I tried adding fresh thyme once—delicious, especially with roasted meats.

Honestly, my biggest mistake was overcrowding the dish. I thought “more is better,” but the onions steamed instead of caramelizing. Stick to the right size pan and don’t pile too high. Consistency comes from sticking to the basics—good ingredients, careful layering, and a little patience. Trust me, with these tips you’ll be serving up a casserole that gets rave reviews every single time.

Variations & Adaptations

The Tennessee Onions Casserole is a classic, but it’s also a blank canvas for your flavor experiments. Here are a few ways you can shake things up:

Gluten-Free: Swap the panko for gluten-free breadcrumbs. I like Schär or homemade—just pulse gluten-free bread in your processor.
Low-Carb/Keto: Use crushed pork rinds or almond flour instead of breadcrumbs for a crunchy, carb-conscious topping.
Vegan/Dairy-Free: Try plant-based cheeses (Daiya or Violife melt well) and use vegan butter. The flavor changes a bit, but the comfort remains.
Seasonal Flavors: In summer, add sliced tomatoes or bell peppers between the onion layers. In fall, toss in sliced apples or a sprinkle of cinnamon for a sweet twist.
Spicy Kick: Substitute pepper jack or add diced jalapeños to the cheese layer for a bold, spicy flavor.
Meaty Additions: Toss in cooked bacon, ham, or sausage for a heartier casserole. I tried crumbled breakfast sausage once—total hit at brunch.

For different cooking methods, you can assemble the casserole in a slow cooker—just layer everything, set to low for 3-4 hours, and finish with the topping under your oven broiler. If you’re cooking for allergies, skip the Parmesan or use a nut-based alternative. My personal go-to? Adding a layer of sliced mushrooms when I want extra earthiness. The possibilities are endless, so don’t be afraid to customize based on what’s in your fridge or the season.

Serving & Storage Suggestions

This Tennessee Onions Casserole is best served piping hot, straight from the oven. The cheese is gooey, the topping is crisp, and the onions are sweet and tender. Here’s how I like to plate it for maximum comfort:

Serving: Use a wide spatula to scoop generous portions. Garnish with a sprinkle of fresh parsley or chives for color. Serve alongside roast chicken, steak, or even just a simple green salad. It’s also perfect with grilled meats at summer barbecues.
Temperature: If you’re prepping ahead, reheat at 350°F (175°C) covered with foil for 15-20 minutes. The flavors settle and get richer as the casserole sits overnight.
Storage: Cool completely before covering tightly with foil or transferring to an airtight container. Refrigerate for up to 4 days. For longer storage, freeze in individual portions for up to 2 months—thaw overnight in the fridge and reheat gently.
Reheating: For best results, reheat covered in the oven or microwave in short bursts. Add a splash of milk or broth if it seems dry.
Flavor Development: Honestly, the flavors deepen after a day in the fridge. The onions mellow and the cheese gets even creamier—my family loves the leftovers!

This casserole holds up well for meal prep, potlucks, or as a make-ahead holiday side. Just don’t be surprised if people ask for seconds before you’ve had a chance to serve dessert!

Nutritional Information & Benefits

Here’s a quick look at what you get in a serving of Tennessee Onions Casserole (about 1/8 of the pan):

Calories: ~280 kcal
Protein: 9g
Carbs: 19g
Fat: 18g
Fiber: 2g
Sugar: 6g

Onions are a great source of vitamin C, antioxidants, and prebiotic fiber—good for your gut and immunity. The cheese provides calcium and protein for strong bones and muscles. If you use whole-grain or gluten-free breadcrumbs, you’ll bump up the fiber even more.

For dietary needs, this casserole can be made gluten-free or vegetarian with simple swaps. It does contain dairy and gluten unless adapted, so watch out for those allergens. Personally, I love how this dish balances indulgence with real, recognizable ingredients—no mystery fillers, just honest comfort food.

Conclusion

If you’re looking for a recipe that delivers big on comfort, flavor, and ease, this Tennessee Onions Casserole is absolutely worth trying. It’s the kind of dish that turns ordinary onions into something crave-worthy, with gooey cheese and a crisp, buttery top that’s pure Southern magic. Plus, you can adapt it to fit almost any dietary need or occasion—what’s not to love?

Don’t hesitate to tweak the cheeses, swap the toppings, or toss in your favorite extras. That’s the beauty of homemade comfort food—it grows with you and your tastes. I make this casserole for family dinners, holiday gatherings, and potlucks, and it always brings smiles (and requests for seconds).

Go ahead, make it your own—and if you do, I’d love to hear how you adapted it! Leave a comment below with your tips, share with friends, or pin it to your favorite Pinterest board. Here’s to cozy meals, happy kitchens, and a casserole that feels like a warm hug every time.

FAQs

Can I make Tennessee Onions Casserole ahead of time?

Absolutely! Assemble it, cover tightly, and refrigerate for up to 24 hours. Bake as directed when ready—just add 5-10 minutes to the baking time if it’s cold from the fridge.

What kind of onions work best for this recipe?

Sweet onions like Vidalia or yellow onions are ideal. Red onions will work but give a slightly sharper taste.

Can I freeze leftovers?

Yes, cool the casserole completely, portion it into airtight containers, and freeze for up to 2 months. Thaw in the fridge and reheat gently in the oven for best texture.

How do I make this casserole gluten-free?

Just swap regular panko breadcrumbs for your favorite gluten-free version. Everything else in the recipe stays the same!

Why did my casserole turn out watery?

This usually happens if the onions were sliced too thin or weren’t seasoned enough before baking. Make sure to slice them thick and use a bit of salt to draw out moisture before layering.