Instructions:

Preheat your oven to the recommended temperature (not specified). Grease and flour a 9-inch round cake pan or line it with parchment paper.

In a large mixing bowl, beat together the unsalted butter, granulated sugar, and light brown sugar on medium speed until light and fluffy, about 2 minutes.

Add the eggs one at a time, mixing well after each addition. Then, mix in the sour cream and vanilla extract until fully combined.

In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually fold the dry ingredients into the wet mixture just until combined, being careful not to overmix.

Gently fold in the blueberries, tossing them with a little flour if using frozen berries to prevent sinking.

In another bowl, prepare the streusel topping by combining the flour, light brown sugar, granulated sugar, and cinnamon. Pour in the melted butter and mix until clumps form; adjust the moisture if necessary.

Pour the batter into the prepared pan, spreading it evenly. Sprinkle the streusel topping over the batter.

Bake in the preheated oven for 32-36 minutes, or until a toothpick inserted in the center comes out clean. Allow the cake to cool in the pan for a few minutes before transferring it to a wire rack to cool completely.

For best results, let the coffee cake cool completely before slicing to guarantee clean cuts. This cake can be stored at room temperature for up to 5 days, in the refrigerator for up to a week, or frozen for up to 2 months.

To enhance the flavor, consider adding a touch of lemon zest or almond extract to the batter for a unique twist. Enjoy your delicious Blueberry Sour Cream Coffee Cake!