Blackberry Crumble Bars

These blackberry crumble bars have a concentrated blackberry filling layered between a soft oat base and a golden crumble topping. The fruit is cooked first to deepen flavor and reduce excess moisture, creating bars that are easy to portion and consistent in texture from edge to center. You can make them with fresh or frozen blackberries.

Course Dessert

Cuisine American

Keyword blackberry bars, blackberry crumble bars, blackberry dessert bars, blackberry oat bars, fruit crumble bars

Prep Time 35

Cook Time 32

Total Time 1 7

Servings large bars or 16 small bars

Calories 210kcal

Author Cathy Pollak

Equipment

baking dish 8x8 (20x20 cm). Keeps bars thick and even.
parchment paper Allows easy removal from the pan.
Saucepan (medium). For cooking the blackberry filling.
2 mixing bowls For dry and wet ingredients.
offset spatula For smoothing the base layer evenly.
Stand Mixer or hand mixer. To cream butter and sugars.

Ingredients

Blackberry Filling:

12 oz (340 g) blackberries fresh or frozen
2 tsps (5 g) lemon zest
1½ tbsps (22 ml) fresh lemon juice
⅓ cup (67 g) granulated sugar
½ tsp 2 g) ground cinnamon
1½ tsps (7 ml) vanilla extract

Crumble and crust:

1½ cups (188 g) all-purpose flour
½ tsp (3 g) sea salt
½ tsp (2 g) baking powder
1 cup (90 g) old-fashioned rolled oats (not quick-cooking oats)
½ cup (113 g) unsalted butter softened
½ cup (100 g) packed light brown sugar
½ cup (100 g) granulated sugar
1 large egg room temperature
1 large egg yolk room temperature
1½ tsps (7 ml) vanilla extract

Instructions

Add the blackberries, lemon zest, lemon juice, sugar, and cinnamon to a medium saucepan set over medium heat. Stir occasionally as the berries begin to release their juices, then mash them to break down any large pieces. Continue cooking, stirring frequently, until the mixture thickens and leaves a visible trail when a spoon is dragged across the bottom of the pan, about 15 minutes. Remove from heat, stir in the vanilla extract, and set aside to cool slightly.
12 oz (340 g) blackberries, 2 tsps (5 g) lemon zest, 1½ tbsps (22 ml) fresh lemon juice, ⅓ cup (67 g) granulated sugar, ½ tsp 2 g) ground cinnamon, 1½ tsps (7 ml) vanilla extract
Preheat the oven to 350°F (175°C). Lightly grease and line an 8x8-inch (20x20 cm) baking pan with parchment paper, leaving an overhang for easy removal.
In a medium bowl, whisk together the flour, salt, and baking powder. Stir in the oats until evenly distributed.
1½ cups (188 g) all-purpose flour, ½ tsp (3 g) sea salt, ½ tsp (2 g) baking powder, 1 cup (90 g) old-fashioned rolled oats
In a separate bowl, beat the butter on medium-low speed until smooth and creamy. Add both sugars and continue mixing until light and fluffy. Add the egg, egg yolk, and vanilla extract, mixing until fully incorporated. Scrape down the sides of the bowl as needed.
½ cup (113 g) unsalted butter, ½ cup (100 g) packed light brown sugar, ½ cup (100 g) granulated sugar, 1 large egg, 1 large egg yolk, 1½ tsps (7 ml) vanilla extract
With the mixer on low speed, add the dry ingredients and mix just until a soft dough forms.
Press about two-thirds of the dough evenly into the prepared baking pan, making sure it reaches all edges. Smooth the surface with an offset spatula if needed. Spread the blackberry filling over the base in an even layer. Crumble the remaining dough over the top.
Bake on the center rack for 32–38 minutes, until the top is lightly golden and set.
Allow the bars to cool in the pan on a wire rack for at least 20 minutes before lifting them out using the parchment overhang. Slice and serve warm or allow to cool completely before cutting for cleaner portions.

Notes

The blackberry filling can be prepared up to 1 week in advance and stored in an airtight container in the refrigerator.
Frozen blackberries can be used without thawing; they may take slightly longer to cook down.
Old-fashioned rolled oats provide the best texture; quick oats will result in a denser bar.
For a more pronounced cinnamon flavor, increase to ½ teaspoon in the filling or add ½ teaspoon to the dry ingredients.
Bars can be cut into 9 larger portions or 16 smaller squares depending on preference.

If you’re making these Blackberry Crumble Bars, check out the full post. That’s where I keep extra tips, FAQs, and details that don’t always make it into the recipe card.

Nutrition info is an estimate and will vary depending on the brands you use.

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Nutrition