Preheat oven to 350°F (175°C).

Grease and flour a 9-inch round cake pan.

Cream butter in a large bowl until smooth.

Gradually add 1 cup of sugar to the butter, beating well at medium speed until light and fluffy.

Add eggs one at a time, beating after each addition until well combined.

In a separate bowl, whisk together flour and baking powder and baking soda.

Gradually add the dry ingredients to the wet ingredients, alternating with the sour cream, beginning and ending with the dry ingredients.

Mix until just combined.

Stir in vanilla extract.

Gently fold in blueberries.

In a small bowl, combine 1 Tbsp sugar and cinnamon.

Sprinkle the cinnamon sugar mixture over the batter.

Pour batter into the prepared cake pan.

Bake for 35-40 minutes, or until a wooden skewer inserted into the center comes out clean.

Let cool in the pan for 10 minutes before inverting onto a wire rack to cool completely.

Dust with powdered sugar, if desired.