Ingredient List:

1. For the Cake:
   • 1/2 cup unsalted butter, softened
   • 1 cup granulated sugar
   • 2 large eggs
   • 1 teaspoon pure vanilla extract
   • 2 cups all-purpose flour
   • 1 teaspoon baking powder
   • 1/2 teaspoon baking soda
   • 1/2 teaspoon salt
   • 1 cup sour cream
   • 1 cup fresh or frozen blueberries
2. For the Streusel Topping:
   • 1/2 cup all-purpose flour
   • 1/4 cup granulated sugar
   • 1/4 cup brown sugar
   • 1/2 teaspoon cinnamon
   • 4 tablespoons unsalted butter, cold and cut into cubes

Baking the Blueberry Sour Cream Coffee Cake

1. Preheat your oven to 350°F (175°C) and grease a 9-inch springform pan.
2. Begin with the cake batter. Cream together butter and sugar until light and fluffy. Beat in the eggs, one at a time, followed by the vanilla extract.
3. In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add the dry mixture to the butter mixture alternately with the sour cream. Fold in the blueberries.
4. Pour the batter into the prepared pan.
5. For the streusel topping, combine the flour, sugars, and cinnamon. Cut in the butter until the mixture resembles coarse crumbs. Sprinkle this over the cake batter.
6. Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean. Allow it to cool before serving.

In conclusion, this delectable blueberry sour cream coffee cake is a fantastic treat to share with family and friends. Its irresistible combination of flavors will surely have everyone reaching for seconds. So, put on your apron and let the baking begin!