• Prep Time: 20 minutes
• Bake Time: 40–45 minutes
• Cooling Time: 1 hour
• Total Time: Approximately 2 hours 5 minutes
• Difficulty: Easy
• Servings: 12 bars

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Ingredients

For the Oat Crumble

• 2 cups old-fashioned rolled oats
• 1½ cups all-purpose flour
• 1 cup light brown sugar, packed
• 1 teaspoon baking powder
• ½ teaspoon ground cinnamon
• ¼ teaspoon salt
• 1 cup unsalted butter, melted
• 1 teaspoon vanilla extract

For the Blueberry Filling

• 3 cups fresh or frozen blueberries
• ⅓ cup granulated sugar
• 2 tablespoons cornstarch
• 1 tablespoon fresh lemon juice
• 1 teaspoon lemon zest
• 1 teaspoon vanilla extract

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Equipment Needed

• 9×13-inch baking pan
• Parchment paper
• Large mixing bowl
• Medium saucepan
• Mixing spoon
• Measuring cups and spoons
• Rubber spatula
• Cooling rack

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Instructions

Step 1: Prepare the Baking Pan

Preheat your oven to 350°F (175°C).

Line a 9×13-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.

Lightly grease the parchment paper if desired.

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Step 2: Make the Oat Crumble Mixture

In a large bowl, combine:

• Rolled oats
• Flour
• Brown sugar
• Baking powder
• Cinnamon
• Salt

Stir until evenly mixed.

Pour in the melted butter and vanilla extract.

Mix until the ingredients resemble moist crumbs.

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Step 3: Form the Crust

Reserve about 1½ cups of the crumble mixture for the topping.

Press the remaining mixture firmly and evenly into the prepared baking pan.

Use the bottom of a measuring cup or glass to create a compact crust.

Bake the crust for 10 minutes, then remove it from the oven.

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Step 4: Prepare the Blueberry Filling

While the crust bakes, combine the blueberries, granulated sugar, cornstarch, lemon juice, and lemon zest in a saucepan.

Cook over medium heat for 5–7 minutes, stirring frequently, until the blueberries begin to burst and the mixture thickens slightly.

Remove from the heat and stir in the vanilla extract.

Allow the filling to cool for a few minutes.

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Step 5: Assemble the Bars

Spread the blueberry filling evenly over the partially baked crust.

Sprinkle the reserved oat crumble mixture evenly across the top.

Do not press the topping down—the loose crumble creates a crisp, textured finish.

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Step 6: Bake

Return the pan to the oven.

Bake for 30–35 minutes, or until:

• The topping is golden brown.
• The blueberry filling is bubbling around the edges.
• The crumble is crisp and lightly toasted.

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Step 7: Cool Completely

Place the pan on a cooling rack.

Allow the bars to cool completely for about 1 hour before slicing.

Cooling helps the filling set, making the bars easier to cut cleanly.

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Step 8: Slice and Serve

Lift the bars from the pan using the parchment paper.

Slice into 12 equal bars.

Serve at room temperature or slightly warm.

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Tips for Perfect Blueberry Oat Crumble Bars

• Use old-fashioned rolled oats rather than quick oats for the best texture.
• Fresh lemon juice brightens the blueberry flavor.
• Frozen blueberries can be used without thawing.
• Allow the bars to cool completely before cutting for neat slices.
• Press the crust firmly to help it hold together after baking.
• Store leftovers in an airtight container to maintain freshness.

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Recipe Variations

Mixed Berry Crumble Bars

Replace half of the blueberries with raspberries, blackberries, or strawberries.

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Almond Blueberry Bars

Add ½ teaspoon almond extract to the filling and sprinkle sliced almonds over the crumble topping.

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Coconut Blueberry Bars

Mix ½ cup shredded coconut into the oat crumble mixture for extra flavor and texture.

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Gluten-Free Version

Use certified gluten-free rolled oats and a gluten-free all-purpose flour blend.

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Lemon Blueberry Crumble Bars

Increase the lemon zest to 2 teaspoons and drizzle the cooled bars with a simple lemon glaze.

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Storage

Store the cooled bars in an airtight container at room temperature for up to 2 days.

For longer storage, refrigerate for up to 5 days.

Separate layers with parchment paper to prevent sticking.

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Freezing Instructions

Wrap individual bars tightly in plastic wrap and place them in a freezer-safe container.

Freeze for up to 3 months.

Thaw overnight in the refrigerator or at room temperature before serving.

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Reheating

Oven

Warm at 300°F (150°C) for 8–10 minutes.

Microwave

Heat individual bars for 15–20 seconds.

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Serving Suggestions

Blueberry Oat Crumble Bars pair wonderfully with:

• Vanilla ice cream
• Fresh whipped cream
• Greek yogurt
• Lemon curd
• Fresh blueberries
• Honey drizzle
• Hot coffee
• Earl Grey tea
• Chamomile tea
• Cold milk

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Why You’ll Love This Recipe

• Easy to prepare
• Buttery oat crumble topping
• Juicy homemade blueberry filling
• Perfect balance of sweet and tart
• Great for breakfast, snacks, or dessert
• Uses simple pantry ingredients
• Freezer-friendly
• Easy to transport
• Family-friendly
• Bakery-quality results at home

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Nutritional Information (Per Bar)

Approximate values:

• Calories: 295 kcal
• Protein: 4 g
• Carbohydrates: 40 g
• Fat: 14 g
• Saturated Fat: 8 g
• Cholesterol: 35 mg
• Sodium: 110 mg
• Fiber: 3 g
• Sugar: 20 g
• Potassium: 110 mg
• Calcium: 30 mg
• Iron: 1.5 mg
• Vitamin C: 6% DV