Ingredients

½ cup butter (melted and cooled)

1 cup brown sugar

1 tsp vanilla

1 large egg (room temperature)

1 large egg yolk (room temperature)

1¼ cups all-purpose flour

1 tsp cornstarch

½ tsp baking powder

½ tsp salt

1 cup blueberries (washed and completely dry)

3 tbsp brown sugar

¼ cup all-purpose flour

½ tsp cinnamon

Pinch of salt

3 tbsp cold butter (diced)

Powdered sugar for topping (optional)

Instructions

Step 1: Preheat your oven to 350°F (175°C). Line an 8×8-inch baking pan with cooking spray and parchment paper, leaving some overhang for easy removal.

Step 2: In a medium bowl, whisk together the melted and cooled butter with 1 cup brown sugar until well combined.

Step 3: Add the egg, egg yolk, and vanilla extract to the butter mixture and mix until smooth.

Step 4: Stir in the cornstarch, baking powder, salt, and 1¼ cups flour until just combined. Gently fold in the dry blueberries, being careful not to crush them.

Step 5: In a small bowl, mix 3 tablespoons brown sugar, ¼ cup flour, cinnamon, and a pinch of salt. Add the cold diced butter and work it into the dry ingredients with a fork or your fingers until the mixture is crumbly and sandy.

Step 6: Pour the blondie batter into the prepared pan and smooth the surface with a spatula. Evenly sprinkle the crumb topping over the batter.

Step 7: Bake for 27 to 32 minutes, or until the top is golden brown and the edges start to pull away from the pan. Allow to cool completely before cutting into squares.

Step 8: Dust with powdered sugar if desired before serving.

Tips & Variations

Make sure the blueberries are completely dry before folding them in to prevent the batter from becoming too wet.

For a different twist, try swapping blueberries for fresh raspberries or chopped strawberries.

You can add a handful of chopped nuts like pecans or walnuts to the batter for extra crunch.

Use room temperature eggs for a smoother batter and better texture.

FAQs

Can I use frozen blueberries instead of fresh?

It’s best to use fresh blueberries for this recipe to avoid excess moisture. If using frozen, thaw and pat them very dry before folding into the batter.

How do I prevent the crumb topping from burning?

Keep an eye on the blondies during the last few minutes of baking. If the topping starts to brown too quickly, tent the pan loosely with foil to protect it while the blondies finish baking.