Blueberry oatmeal crumble bars are a versatile and satisfying treat that can be enjoyed any time of day. Featuring a buttery oat crust, a vibrant blueberry filling, and a golden, crisp crumble topping, this recipe strikes an elegant balance between comfort and nutrition.
Whether served as a quick breakfast, an afternoon snack, or a light dessert, these bars are as easy to prepare as they are enjoyable to eat.
Why This Recipe Works
Balanced Flavor and Texture
The combination of tender oats, a bright blueberry center, and a buttery crumble provides a delightful contrast in both texture and flavor. The natural sweetness of blueberries is enhanced with a hint of lemon, while the oat layers offer a hearty, rustic feel.
Streamlined Preparation
This recipe utilizes a single oat-based mixture for both the crust and the topping, simplifying the process without compromising quality. With minimal steps and easy-to-source ingredients, it’s an excellent option for both beginner and experienced bakers.
Flexible and Adaptable
Fresh or frozen blueberries work equally well in this recipe, making it suitable for any season. The bars are also easily customizable to fit dietary preferences or ingredient availability.
Ingredients Overview
For the Crust and Crumble
- 1 cup (125g) all-purpose flour – Provides structure and a tender bite.
- 3/4 cup (75g) old-fashioned rolled oats – Adds texture and heartiness.
- 1/2 cup (100g) granulated sugar – Sweetens the crust and topping.
- 1/4 cup (50g) packed brown sugar – Brings depth and a hint of molasses.
- 1/2 tsp ground cinnamon – Adds subtle warmth.
- 1/4 tsp salt – Enhances overall flavor balance.
- 1/2 cup (113g) unsalted butter, melted – Binds the mixture and adds richness.
- 1 large egg yolk – Helps bind the crust, contributing to a tender, cohesive base.
For the Blueberry Filling
- 2 cups (300g) blueberries (fresh or frozen) – The featured ingredient, offering natural sweetness and vibrant color.
- 1 tbsp freshly squeezed lemon juice – Brightens the flavor.
- 1/4 cup (50g) granulated sugar – Enhances the fruit’s natural sweetness.
- 2 tsp cornstarch – Thickens the filling during baking.
Step-by-Step Instructions
Step 1: Preheat and Prepare
Preheat oven to 350°F (175°C). Line an 8×8-inch baking pan with parchment paper, leaving an overhang on the sides to assist with removal after baking.
Step 2: Make the Crust and Topping
In a medium mixing bowl, combine flour, oats, both sugars, cinnamon, and salt. Stir to blend. Add the melted butter and egg yolk, mixing until the mixture becomes crumbly.
Set aside approximately 1 cup of this mixture for the topping. Press the remaining mixture evenly into the bottom of the prepared pan to form a firm base.
Step 3: Prepare the Blueberry Filling
In a separate bowl, combine the blueberries, lemon juice, granulated sugar, and cornstarch. Stir gently to coat the berries evenly.
Step 4: Assemble
Spread the blueberry mixture evenly over the crust. Crumble the reserved oat mixture over the top, gently pressing it into clusters for added texture.
Step 5: Bake
Bake for 45–55 minutes, or until the crumble is golden brown and the filling is bubbling at the edges. If using frozen berries, baking time may need to be extended by a few minutes.
Step 6: Cool and Slice
Allow the bars to cool completely in the pan for at least 3 hours before slicing. This ensures clean cuts and a well-set filling. Use the parchment overhang to lift the bars from the pan before slicing.
Tips for Success
- Use Rolled Oats: Old-fashioned rolled oats offer optimal texture. Avoid quick or instant oats, which can make the bars overly soft.
- Add Lemon Zest: Incorporating 1–2 teaspoons of lemon zest into the filling can enhance the flavor and provide a bright citrus note.
- Allow to Cool Completely: Proper cooling is essential for structure. Chill in the refrigerator to speed up the process if needed.
Variations and Substitutions
- Alternate Berries: Substitute blueberries with raspberries, blackberries, or a berry blend. If using juicier berries, add extra cornstarch to prevent excess moisture.
- Gluten-Free Option: Replace all-purpose flour with a 1:1 gluten-free flour blend and use certified gluten-free oats.
- Lower Sugar: Reduce the granulated sugar in the crust to 1/3 cup and the brown sugar to 2 tablespoons. The filling can also be sweetened with just 2 tablespoons of sugar for a less sweet version.
Storage and Freezing
- Room Temperature: Store in an airtight container for up to 4 days.
- Refrigeration: Keeps fresh for up to 1 week when refrigerated.
- Freezing: Wrap individual bars tightly in plastic wrap and freeze for up to 3 months. Thaw overnight in the refrigerator and reheat briefly if desired.
Nutritional Information (Per Bar)
- Calories: 191
- Fat: 9g
- Saturated Fat: 5g
- Cholesterol: 30mg
- Sodium: 60mg
- Carbohydrates: 27g
- Fiber: 2g
- Sugar: 15g
- Protein: 2g
Frequently Asked Questions
Can I use frozen blueberries?
Yes. Frozen blueberries can be added directly to the filling mixture without thawing. Bake time may need to be extended slightly.
How do I prevent the crust from becoming soggy?
Ensure the blueberries are well coated with cornstarch and press the crust firmly into the pan before adding the filling.
Can this recipe be doubled?
Absolutely. For a larger batch, double all ingredients and bake in a 9×13-inch pan. Bake time will remain similar; check for bubbling filling and golden topping.
Conclusion
Blueberry oatmeal crumble bars are a crowd-pleasing, wholesome treat that can be enjoyed at any time of day. With their simple preparation, adaptable ingredients, and delicious results, they’re a wonderful addition to any baker’s repertoire.
We invite you to try this recipe and share your results. Whether you make it exactly as written or add your own twist, these bars are sure to impress.