Blueberry Oatmeal Crumble Bars Recipe Easy Dessert Squares

There’s something magical about biting into a soft, buttery crumble bar packed with juicy blueberries and a hearty oat base. These blueberry oatmeal crumble bars are the perfect dessert squares to satisfy your sweet tooth while still feeling homemade and comforting. Whether you’re prepping for a casual gathering, a picnic, or just a treat-yourself moment, this recipe will quickly become your go-to. The best part? They’re incredibly easy to whip up!

What I love most about these bars is how they bring together contrasting textures—the crunch of the crumble, the tenderness of the oat layer, and the burst of fresh blueberries. And don’t even get me started on the smell that fills your kitchen as they bake—pure heaven! If you’ve never made crumble bars before, trust me, this is the recipe to start with.

The Story Behind Blueberry Oatmeal Crumble Bars

This recipe holds a special place in my heart. It all started with a family trip to a blueberry farm one summer. We picked way too many blueberries, and by the end of the week, there were still bowls of them left in the fridge. My grandmother, ever the problem solver, turned them into the most delicious dessert squares. That was my first time tasting blueberry oatmeal crumble bars, and I was hooked!

While the original recipe was passed down from my grandmother, I’ve tweaked it over the years to make it my own. I wanted a dessert that felt indulgent but also had that wholesome oat base—a perfect balance of sweet and hearty. Blueberries are such a versatile fruit; they’re packed with antioxidants and work beautifully in baked goods. Plus, they’re in season during the summer, making this recipe even better when you can use fresh berries.

Over time, these bars have become a staple in my kitchen. I love how they can be easily customized depending on what’s in season or what I have in my pantry. While they’re perfect for summer, they can also be made with frozen berries, giving you a taste of sunshine year-round.

Ingredients for Blueberry Oatmeal Crumble Bars

The beauty of this recipe lies in its simplicity. Most of the ingredients are pantry staples, but every component plays a crucial role in the final flavor and texture of the bars.

• Blueberries: Fresh or frozen both work well. Fresh berries are ideal during peak season, but frozen blueberries are a great alternative when fresh ones aren’t available. Just don’t thaw them before using!
• Old-fashioned oats: These give the bars their hearty, chewy texture. Avoid quick oats as they can make the base too mushy.
• All-purpose flour: You’ll need this for both the crumble and the base. If you’re gluten-free, you can substitute with a 1:1 gluten-free baking flour.
• Butter: Unsalted butter works best. Make sure it’s cold when you’re incorporating it into the crumble for a perfect texture.
• Brown sugar: Adds a deep, caramel-like sweetness to the bars. You can substitute with coconut sugar if you prefer.
• Granulated sugar: Used to sweeten the blueberry filling while letting the natural berry flavor shine through.
• Lemon juice: A splash of lemon juice brightens up the blueberry filling and balances the sweetness.
• Cornstarch: Helps thicken the filling so you get that perfect jammy consistency.
• Vanilla extract: Adds warmth and depth to the crumble.

All of these ingredients come together to create layers of flavor and texture that you’ll absolutely love. And don’t worry—if you’re missing an ingredient, there are plenty of substitutions you can use!

Equipment You’ll Need

One of the best things about this recipe is that it doesn’t require any fancy equipment. Here’s what you’ll need:

• 9×13 baking dish: This size works perfectly to create bars with the right thickness.
• Mixing bowls: You’ll need a couple of bowls to mix the base, crumble, and filling separately.
• Pastry cutter or fork: For blending the butter into the crumble mixture. If you don’t have one, clean hands work just fine!
• Measuring cups and spoons: Precision is key, especially when baking.
• Parchment paper: Makes removing the bars from the pan so much easier.

If you don’t have a pastry cutter, don’t stress—just use your fingers to gently mix the butter into the dry ingredients. It’s a bit messier, but it works like a charm!

How to Make Blueberry Oatmeal Crumble Bars

1. Preheat your oven: Set it to 350°F (175°C) and line your baking dish with parchment paper.
2. Make the crumble: In a mixing bowl, combine 1 1/2 cups (150g) of oats, 1 1/2 cups (190g) of flour, 3/4 cup (150g) of brown sugar, and 3/4 cup (170g) of cold, cubed butter. Use a pastry cutter or fork to blend until the mixture is crumbly and holds together when pressed.
3. Press the base: Take two-thirds of the crumble mixture and press it firmly into the bottom of your prepared pan. Bake for 12-15 minutes or until lightly golden.
4. Prepare the blueberry filling: In another bowl, toss 3 cups (450g) of blueberries with 1/4 cup (50g) of granulated sugar, 2 tablespoons (15g) of cornstarch, and 1 tablespoon (15ml) of lemon juice. Spread this mixture evenly over the baked crust.
5. Top with crumble: Sprinkle the remaining crumble mixture over the blueberries, gently pressing it down.
6. Bake: Return the pan to the oven and bake for 30-35 minutes, or until the top is golden and the blueberries are bubbling.
7. Cool and slice: Let the bars cool completely in the pan before slicing into squares. This step is crucial to ensure clean cuts!

And that’s it! Your kitchen should now smell absolutely amazing.

Cooking Tips & Techniques

Here are some helpful tips to ensure your bars turn out perfectly every time:

• For the best crumble texture, make sure your butter is cold. This helps create those delicious, buttery clusters.
• If using frozen blueberries, don’t thaw them before mixing with the other filling ingredients. Thawed berries release too much liquid.
• Press the base firmly into the pan to prevent it from crumbling when slicing the bars.
• Let the bars cool completely before cutting. I know it’s tempting to dig in right away, but patience pays off!

These small details can make a big difference in the final result.

Variations & Adaptations

Want to switch things up? Here are some fun variations to try:

• Mixed berry bars: Replace half of the blueberries with raspberries, blackberries, or strawberries for a colorful twist.
• Gluten-free option: Use a gluten-free all-purpose flour and certified gluten-free oats.
• Nutty crumble: Add 1/4 cup (30g) of chopped almonds or pecans to the crumble mixture for extra crunch.
• Vegan version: Swap the butter with a plant-based alternative and use maple syrup instead of brown sugar.

Feel free to experiment and make this recipe your own!

Serving & Storage Suggestions

These bars are best served slightly warm or at room temperature. Pair them with a scoop of vanilla ice cream or a dollop of whipped cream for an extra treat. They’re also great with a cup of coffee or tea for an afternoon snack.

To store, place the bars in an airtight container and refrigerate for up to 5 days. For longer storage, freeze them for up to 3 months. Just let them thaw at room temperature before serving.

Nutritional Information & Benefits

Each bar is approximately 220 calories, with 9g of fat, 31g of carbohydrates, and 3g of protein. The blueberries provide a healthy dose of antioxidants, while the oats offer fiber and a touch of heartiness.

This recipe is a satisfying balance of indulgence and nutrition, making it a great choice when you want something sweet without going overboard.

Conclusion

These blueberry oatmeal crumble bars are a must-try for anyone who loves easy, delicious desserts. They’re versatile, packed with flavor, and perfect for any occasion. Plus, they’re a great way to use up fresh or frozen blueberries!

I’d love to hear how your crumble bars turn out! Leave a comment below with your thoughts or any tweaks you made to the recipe. And if you enjoyed this, don’t forget to share it with your friends or pin it for later. Happy baking!

FAQs

Can I use frozen blueberries for this recipe?

Yes, frozen blueberries work perfectly! Just make sure not to thaw them before using.

How do I make these bars gluten-free?

You can substitute the all-purpose flour with a gluten-free baking flour and use certified gluten-free oats.

Can I substitute the blueberries with another fruit?

Absolutely! Try raspberries, blackberries, or diced strawberries for a fun variation.

How do I store leftover bars?

Keep them in an airtight container in the fridge for up to 5 days, or freeze for up to 3 months.

What’s the best way to serve these bars?

They’re delicious on their own, but pairing them with ice cream or whipped cream takes them to the next level!

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