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blueberry blondie with a bite taken out.
5 from 9 votes
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Blueberry Crumble Blondies

Classic blueberry blondies get a twist into this blueberry crumble blondie! The perfectly chewy and fudgy batter is swirled with fresh blueberry jam and topped with a buttery crumb to taste just like blueberry crumble!
Servings 9 servings
Prep 25 mins
Cook 28 mins
Total 53 mins
Course : Breakfast, Dessert
Cuisine : American
Author : Cambrea Gordon


Blueberry Jam Filling

  • 1 cup frozen small wild blueberries
  • ¼ teaspoon lemon zest
  • 1 teaspoon lemon juice
  • 2 tablespoon granulated sugar
  • 2 teaspoon corn starch
  • 2 teaspoon water


Blondie Batter

  • 1 large egg
  • 1 large egg yolk
  • cup light brown sugar packed
  • ¼ cup granulated sugar
  • 1 teaspoon vanilla extract
  • ½ cup unsalted butter melted
  • 1 cup + 2 tbsp all-purpose flour
  • ¼ teaspoon baking powder
  • ½ teaspoon salt
  • ¼ cup frozen small wild blueberries for the top


  • Line a square 8x8 baking pan with parchment paper and preheat the oven to 350 F/180 C.

Make the Jam

  • Combine the frozen blueberries, lemon zest, lemon juice, and sugar in a small pot. Cook over medium heat for 8-9 minutes or until the berries start to release their juices and boil.
    1 cup frozen small wild blueberries, ¼ teaspoon lemon zest, 1 teaspoon lemon juice, 2 tablespoon granulated sugar
  • Whisk together the cornstarch and water.
    2 teaspoon corn starch, 2 teaspoon water
  • Pour the cornstarch slurry into the jam and cook for 1-2 minutes longer until the jam is super thick. Then transfer it to a bowl and set it aside to cool completely.

Make the Crumb

  • In a small bowl, combine the flour, sugar, brown sugar, and melted butter. Place the bowl in the freezer to chill the crumb while you make the blondie batter. Before using, use your hands to break up the crumb into small peices.
    ¼ cup all-purpose flour, 1 tablespoon granulated sugar, 1 tablespoon light brown sugar, 2 tablespoon unsalted butter

Make the Batter

  • In a medium bowl, whisk together the egg, egg yolk, vanilla, brown sugar and sugar until light and pale in color.
    1 large egg, 1 large egg yolk, ⅔ cup light brown sugar, ¼ cup granulated sugar, 1 teaspoon vanilla extract
  • Whisk in the melted butter.
    ½ cup unsalted butter
  • Fold in the flour, baking powder, and salt until just combined.
    1 cup + 2 tablespoon all-purpose flour, ¼ teaspoon baking powder, ½ teaspoon salt
  • Evenly spread the batter into the prepared pan.
  • Dollop the cooled blueberry jam on top of the batter and use a spatula to evenly spread it over the top. The jam will mix some with the batter which is okay!
  • Sprinkle the crumb and the frozen blueberries on top.
    ¼ cup frozen small wild blueberries
  • Bake for 28-30 minutes, or until the middle is puffy, the edges are golden brown, and a toothpick inserted into the center comes out with just a few moist crumbs.
  • Let cool completely before cutting then enjoy!


Step by step process photos are provided above, in the body of this post.
  • Use a kitchen scale: Baking with a scale is faster, easier, and overall much more accurate than cup measurements.
  • Use room temperature ingredients: Using room temperature ingredients creates a smooth, fully blended batter that will result in a uniform texture and even baking.
  • Dark vs. light baking trays: Baking pans conduct heat differently depending on what color it is. If your pan is dark or black you should decrease the heat to 325 F/163 C.
  • Cooking times may vary: All ovens are different, and your bars may bake quicker or take longer than the indicated baking time. I recommend always checking on them occasionally and testing for doneness!
  • Can I use regular frozen blueberries or fresh blueberries? This recipe does best with the frozen small wild blueberries. Fresh blueberries will take longer to cook down and the flavor overall isn't as strong!
  • Storage: Once cool, store the cut bars in a bag or sealed container at room temperature for 3-4 days.
  • Freezing: Store the cut bars in a sealed container or freezer bag for up to 1 month!


Serving: 1serving | Calories: 220kcal | Carbohydrates: 26g | Protein: 1g | Fat: 13g | Saturated Fat: 8g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 4g | Trans Fat: 1g | Cholesterol: 55mg | Sodium: 149mg | Potassium: 44mg | Fiber: 1g | Sugar: 24g | Vitamin A: 431IU | Vitamin C: 2mg | Calcium: 29mg | Iron: 1mg