Preheat your oven to 350°F (175°C).

Grease a 9-inch round cake pan with butter or cooking spray.

In a large mixing bowl, whisk together flour, sugar, baking powder, baking soda, and salt.

Add the softened butter to the dry ingredients and mix until crumbly.

Mix in the eggs and vanilla extract until fully combined.

Stir in the sour cream until smooth.

Gently fold in the fresh blueberries with a rubber spatula.

Pour the batter into the prepared pan and smooth the top.

Bake for 30 to 35 minutes or until a toothpick inserted comes out clean.

Let the cake cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.