Heavenly Blueberry Coffee Cake Recipe

Preheat your oven to 350°F (175°C).
Grease a 9x9 inch square baking pan with butter or cooking spray.
In a small bowl, combine 1/4 cup granulated sugar, 1/4 cup brown sugar, and 1 teaspoon cinnamon.
Cut in 1/4 cup (1/2 stick) of softened butter using a pastry cutter or fork until the mixture resembles coarse crumbs. Set aside.
In a large mixing bowl, cream together 1/2 cup softened butter and 3/4 cup granulated sugar until light and fluffy.
Beat in 2 eggs, one at a time, until well combined.Stir in 1 teaspoon vanilla extract.
In a separate bowl, whisk together 2 cups all-purpose flour, 2 teaspoons baking powder, and 1/2 teaspoon salt.
Gradually add the dry ingredients to the wet ingredients, alternating with 1/2 cup sour cream or yogurt, until just combined. Be careful not to overmix.
Gently fold in 1 to 1 1/2 cups of blueberries until evenly distributed.
Pour the batter into the prepared baking pan, spreading it out evenly.
Sprinkle the streusel topping evenly over the batter.
Bake in the preheated oven for 30 to 40 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the cake from the oven and let it cool in the pan for about 10 to 15 minutes.
After cooling slightly, transfer the cake to a wire rack to cool completely before slicing and serving.