St. Patrick’s Mint Oatmeal Cookie Bars – Easy Chocolate Chip Dessert

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mandy

Posted on December 24, 2025

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Dessert Recipes

December 24, 2025

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Picture this: The kitchen is filled with the irresistible aroma of creamy mint and melty chocolate, the kind that makes you stop mid-task just to breathe it all in. The first time I pulled a pan of these St. Patrick’s Mint Oatmeal Cookie Bars with Chocolate Chips out of the oven, I knew I was onto something magical. The crackly golden top, the flash of green from the mint, and the gooey chocolate all mingled together in a way that felt like a celebration. It’s the sort of dessert that whispers, “Just one more piece won’t hurt,” and honestly, who can blame you?

My journey with these cookie bars started when I was knee-high to a grasshopper, watching my grandmother bake her famous oatmeal cookies every March. She’d add a secret splash of mint just for St. Paddy’s Day, and that little twist stuck with me. Years later, I found myself craving that old-school comfort but wanted something even more decadent—so I threw in a heap of chocolate chips and pressed the dough into a bar pan. Let’s face it, bars are just easier for sharing (or for sneaking bites from the fridge at midnight, don’t judge!).

The first batch disappeared before they’d even cooled. My kids, husband, and even our next-door neighbor kept coming back for “just a little sliver.” I’ve made these for school bake sales, rainy weekends, and, of course, as the star of our St. Patrick’s Day spread. There’s something about the fresh minty bite paired with hearty oats and pools of chocolate that just feels like a warm hug. This recipe quickly turned into a staple for family gatherings and gifting to friends who need a pick-me-up. Trust me, you’re going to want to bookmark this one—it’s dangerously easy, endlessly comforting, and always the first to vanish from the dessert table (in the name of research, I’ve tested that theory many times!).

Why You’ll Love These St. Patrick’s Mint Oatmeal Cookie Bars

After making these St. Patrick’s Mint Oatmeal Cookie Bars with Chocolate Chips more times than I can count, I can honestly say they’re a crowd-pleaser for all the right reasons. Years of baking (and a few flops along the way) taught me what makes a cookie bar truly unforgettable, and these check all the boxes.

Quick & Easy: Ready in under 40 minutes, you won’t need to clear your afternoon. Perfect for a last-minute dessert or when you just want something sweet, fast.
Simple Ingredients: No fancy shopping trips. If you’ve got oats, chocolate chips, and a bottle of mint extract, you’re halfway there.
Perfect for St. Patrick’s Day (or any day): The pop of green and minty freshness make these a festive must, but honestly, they’re welcome at brunches, potlucks, or as a cozy after-dinner treat year-round.
Crowd-Pleaser: Kids devour them. Adults sneak seconds. I once caught my best friend pocketing a few for the road. Enough said.
Unbelievably Delicious: The mix of chewy oats, bright mint, and gooey chocolate is pure comfort. It’s the kind of flavor that makes you close your eyes for a second and just savor.

What sets these bars apart? It’s all about that minty twist—subtle but unmistakable, never toothpaste-y, just cool enough to liven up the classic oatmeal cookie base. I blend the mint right into the dough, so every bite gets a little spark of green goodness. And, let’s not forget, the oatmeal gives them a hearty texture that’s both chewy and soft, while the chocolate chips melt into pockets of joy.

This isn’t just another cookie bar recipe. It’s the one you’ll make when you want a treat that tastes like nostalgia, but with a modern, festive touch. If you’re aiming to impress without breaking a sweat—or just want to add a little luck of the Irish to your dessert table—these bars are your new go-to. I promise, you’ll be making them long after St. Patrick’s Day has come and gone!

What Ingredients You Will Need

This recipe uses simple, wholesome ingredients to deliver bold flavor and a satisfying, chewy texture without a fuss. Most are pantry staples—no need for a special grocery run. Here’s what you’ll need to make your batch of St. Patrick’s Mint Oatmeal Cookie Bars with Chocolate Chips:

For the Dough:
- 1 cup (226 g) unsalted butter, softened (adds richness and helps bars stay moist)
- 1 cup (200 g) light brown sugar, packed (for chewiness and caramel notes)
- 1/2 cup (100 g) granulated sugar (balances the brown sugar for sweetness)
- 2 large eggs, room temperature (binds everything together and adds lift)
- 2 teaspoons pure vanilla extract (use a good brand for depth)
- 1 1/2 teaspoons mint extract (I like McCormick or Nielsen-Massey for a clean flavor—don’t use peppermint oil, it’s too strong!)
- Green food coloring, optional (for that festive St. Patrick’s Day flair—5-8 drops, or until you reach your desired shade)
- 2 cups (250 g) all-purpose flour (King Arthur flour is my go-to for consistent results)
- 2 cups (180 g) old-fashioned rolled oats (gives that classic chew; quick oats can work in a pinch, but texture will be softer)
- 1 teaspoon baking soda (for lift)
- 1/2 teaspoon salt (balances flavors)
For the Mix-Ins:
- 1 1/2 cups (270 g) semi-sweet chocolate chips (I recommend Ghirardelli or Guittard—use mini chips for more even distribution, or chunks for big chocolate pockets)
- 1/2 cup (85 g) chopped dark chocolate or Andes mints, optional (for extra decadence and more minty flavor)

Ingredient Tips:

Butter: If you need a dairy-free version, swap in vegan margarine (like Earth Balance), though bars might be a touch softer.
Eggs: For egg-free, sub in 1/2 cup unsweetened applesauce (texture changes a smidge but still tasty).
Flour: You can use a 1:1 gluten-free blend if needed (Bob’s Red Mill works well here).
Oats: Make sure they’re certified gluten-free if allergies are a concern.
Mint Extract: NOT peppermint oil—too concentrated! If you don’t have mint extract, you can use peppermint, but cut the amount in half.

Honestly, these are endlessly adaptable—feel free to experiment with what you have on hand.

Equipment Needed

9×13-inch (23×33 cm) baking pan: I’ve used both glass and metal pans; metal gives a crisper edge while glass stays chewier. Lining with parchment paper makes lifting the bars out a breeze.
Mixing bowls: One large for wet ingredients, one medium for dry. If you only have one, just wipe it out between steps.
Electric mixer or sturdy whisk: A stand mixer makes things fast, but a hand mixer or good old-fashioned elbow grease works just fine.
Measuring cups and spoons: For accuracy, especially with the flour and oats.
Rubber spatula: For scraping down the bowl and spreading dough evenly.
Wire cooling rack: Helps bars cool evenly (I’ve also just used an inverted muffin tin in a pinch!)

If you don’t have a 9×13-inch pan, two 8×8-inch (20×20 cm) pans will do the trick—just check for doneness a few minutes earlier. For easy cleanup, parchment paper is your best friend (just don’t skimp on the overhang for easy lifting!). Budget tip: Dollar store pans work well here since bars aren’t fussy about even heat like cakes are.

Preparation Method

Preheat and Prep the Pan: Preheat your oven to 350°F (175°C). Line a 9×13-inch (23×33 cm) baking pan with parchment paper, leaving a little overhang on the long sides. Lightly spray with nonstick spray for easier release.
Cream Butter and Sugars: In a large bowl, cream 1 cup (226 g) softened unsalted butter with 1 cup (200 g) brown sugar and 1/2 cup (100 g) granulated sugar. Beat for about 2 minutes (medium speed if using a mixer) until light and fluffy. If your butter isn’t soft enough, microwave it in 5-second bursts until just pliable.
Add Eggs, Vanilla, and Mint: Add 2 large eggs, 2 teaspoons vanilla extract, and 1 1/2 teaspoons mint extract to the butter mixture. Mix until well combined and smooth. If using food coloring, add 5-8 drops now and blend until you get a nice green (it’ll look a little bright, but it mellows after baking).
Combine Dry Ingredients: In a medium bowl, whisk together 2 cups (250 g) all-purpose flour, 2 cups (180 g) rolled oats, 1 teaspoon baking soda, and 1/2 teaspoon salt. Make sure there are no lumps—oats can sometimes clump up.
Mix Wet and Dry: Gradually add the dry mixture to the wet, stirring gently with a rubber spatula or mixer on low. Stop as soon as the flour disappears; overmixing can make the bars tough.
Add Chocolate Chips and Mix-Ins: Fold in 1 1/2 cups (270 g) chocolate chips (and any optional Andes mints or chopped dark chocolate, if using). The dough will be thick—use some muscle!
Spread in Pan: Transfer the dough to your prepared pan. Press it evenly into the corners with a spatula or your hands (dampened fingers help prevent sticking). Aim for an even layer so the bars bake uniformly.
Bake: Bake for 22-27 minutes, until the top is just set and lightly golden. A toothpick inserted near the center should come out with moist crumbs but not raw batter. If your oven runs hot, check at 20 minutes (every oven is quirky).
Cool Completely: Let the bars cool in the pan for at least 30 minutes, then lift them out using the parchment overhang. Transfer to a wire rack to cool fully before slicing. If you cut too soon, they’ll be gooey and fall apart (tempting, but patience pays off here!).
Slice and Serve: For clean squares, use a sharp knife wiped clean between cuts. I usually cut 24 bars, but you can go bigger or smaller depending on your crowd.

Troubleshooting Tips: If the top is browning too quickly, tent with foil. If the bars seem underbaked in the center, give them 2-3 more minutes—better a little gooey than dry! For extra flair, drizzle with melted chocolate before serving.

Cooking Tips & Techniques

Years of cookie bar baking (and, let’s be honest, a few disasters) taught me a few tricks for perfect St. Patrick’s Mint Oatmeal Cookie Bars with Chocolate Chips every time:

Room-Temperature Ingredients: Using eggs and butter at room temp helps everything blend smoothly, giving you a uniform texture. Cold butter can leave lumps, and cold eggs can make the dough seize.
Don’t Overmix: Once you add the flour and oats, mix just until combined. Overmixing leads to tough bars. If you see a little flour streak, that’s okay—it’ll mix in as you fold in the chips.
Measuring Flour: Spoon flour into your measuring cup, then level with a knife. Scooping straight from the bag packs it down and makes bars dry. If you have a kitchen scale, even better!
Even Spreading: The dough is sticky. Lightly wet your hands or spatula to press it into the pan without frustration.
Watching Bake Time: Ovens vary. Start checking at the lower end of the bake time. Look for a set top and slightly pulling away from the edges. Underbaked is better than overbaked!
Chocolate Chip Distribution: Toss chips in a little flour before folding in—they won’t all sink to the bottom.
Color Cues: If you want a brighter green, add more food coloring, but remember it’ll fade a bit as it bakes.
Let Bars Cool Completely: I know, waiting is tough, but bars slice much neater once cool.

I’ve made the mistake of using too much mint extract once—it was…medicinal. Stick with mint, not peppermint, and measure carefully. And if all else fails, a drizzle of melted chocolate or a sprinkle of mini chips on top hides any imperfections (been there, done that!).

Variations & Adaptations

One of my favorite things about these St. Patrick’s Mint Oatmeal Cookie Bars with Chocolate Chips is how easy they are to tweak for any occasion, craving, or dietary need:

Gluten-Free: Swap the all-purpose flour for a 1:1 gluten-free baking mix and use certified gluten-free oats. I’ve done this for friends with allergies, and nobody noticed the difference!
Vegan: Use plant-based butter (like Earth Balance), replace eggs with flax eggs (2 tablespoons ground flax + 5 tablespoons water, mixed and rested for 5 minutes), and make sure your chocolate chips are dairy-free. The texture will be a little softer but still delicious.
Double Mint: Stir in 1/2 cup crushed Andes mints or mint candies for even more minty flavor. I tried this last year, and my husband claimed it was the “best yet.”
White Chocolate or Dark Chocolate Chips: Swap semi-sweet for white or dark chips for a new flavor profile. White chocolate and mint is a classic combo!
Seasonal Flavors: For a spring twist, add 1/2 cup chopped pistachios or walnuts. For Christmas, toss in some red and green sprinkles.
No-Mint Version: If someone in your crowd isn’t into mint (it happens), just leave out the extract and coloring. You’ll have classic oatmeal chocolate chip bars—still a winner!
Nut-Free: These are naturally nut-free but always check your chocolate chips if allergies are a concern.

Honestly, don’t be afraid to experiment. I once added a layer of marshmallow fluff in the middle for a s’mores vibe—messy, but so good. Let your taste buds lead the way!

Serving & Storage Suggestions

These St. Patrick’s Mint Oatmeal Cookie Bars with Chocolate Chips are best served at room temperature, where the chocolate is still a little soft and the mint flavor shines. Slice them into neat squares or even cut them into shamrock shapes for a themed party (kids love this!).

Presentation Ideas: Arrange on a festive platter, dust with powdered sugar, or drizzle with extra melted chocolate for a bakery-worthy finish. They pair perfectly with a cold glass of milk, hot coffee, or even a mug of Irish cream for the grown-ups.

Storage: Store bars in an airtight container at room temperature for up to 4 days. To keep them extra chewy, add a slice of bread to the container (just like grandma did!). For longer storage, freeze bars (layered with parchment) for up to 2 months. Thaw at room temperature or zap in the microwave for 10-15 seconds for that fresh-baked taste.

Honestly, the flavors get even better on day two as the mint and chocolate meld together. If you like them warm, a quick 10-second microwave blast brings back the gooey chocolate magic. They travel well—great for lunchboxes, picnics, or mailing in care packages.

Nutritional Information & Benefits

Each St. Patrick’s Mint Oatmeal Cookie Bar (based on 24 bars) comes in around 210 calories, with 3g protein, 27g carbs, and 10g fat. There’s a little fiber from the oats and a touch of iron from the chocolate.

Health Highlights: Old-fashioned oats add whole grain goodness and a chewy texture that’s more satisfying (and filling) than your average dessert. Using dark chocolate chips bumps up the antioxidants, and you can always scale back the sugar if you like things less sweet. For gluten-free or vegan folks, these bars are easily adapted with simple swaps—no one misses out.

Potential allergens include wheat (flour), dairy (butter, chocolate chips), and eggs. For nut allergies, just double-check your chocolate chips and avoid nut mix-ins. Personally, I love knowing these bars are made from real ingredients you can pronounce, with no weird preservatives or artificial flavors (unless you count the green food coloring—which is totally optional for a festive touch!).

Conclusion

There’s just something special about these St. Patrick’s Mint Oatmeal Cookie Bars with Chocolate Chips. They’re festive, easy, and packed with that nostalgic, comforting flavor I crave every March (and, honestly, the rest of the year too). Whether you’re baking for a crowd, gifting a sweet treat, or just treating yourself, this recipe is one you’ll reach for again and again.

I love that you can tweak them to fit any taste or diet, and they never fail to bring a smile to anyone who tries them. Don’t be afraid to make these your own—change up the chips, play with the mint, or add your favorite mix-ins. If you try them, I’d love to hear what you think! Drop a comment below, share your photos, or let me know your favorite variation.

Bake a batch, share the luck, and let your kitchen smell like pure happiness. You’re going to want to keep this recipe close—it’s a keeper, for sure!

Frequently Asked Questions

Can I use peppermint extract instead of mint extract?

You can, but peppermint is much stronger. Use half the amount, so about 3/4 teaspoon. The flavor will be a little sharper, but still delicious!

Can I make these bars gluten-free?

Absolutely! Substitute a 1:1 gluten-free flour blend and use certified gluten-free oats. I do this often for friends with allergies, and the texture is still spot on.

What if I don’t have green food coloring?

No problem—the bars will taste the same, just minus the festive green hue. You can leave it out or try a natural food coloring if you prefer.

How do I store leftover cookie bars?

Keep them in an airtight container at room temperature for up to 4 days, or freeze for up to 2 months. They stay chewy and delicious either way!

Can I double the recipe for a crowd?

Yes! Double all ingredients and bake in two 9×13-inch pans, or use a large rimmed baking sheet. Check for doneness a few minutes early, as thin bars bake faster.

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