Preheat your oven to 350°F (175°C) and prepare a 12-cup muffin tin with liners.

In a medium bowl, whisk together flour, baking powder, baking soda, and salt; set aside.

In another bowl, mix sour cream, milk, and 2 tablespoons lemon juice until combined; set aside.

Toss blueberries with remaining lemon juice and a touch of flour to coat.

Cream butter until fluffy, then gradually add sugar and optional lemon extract.

Add eggs one at a time, mixing well after each.

Alternately combine flour mixture and sour cream mixture, mixing until just combined.

Gently fold in blueberries and lemon zest.

Divide batter among muffin cups, fill about 3/4 full, and bake for 16-20 minutes or until a toothpick comes out clean.

Cool the cupcakes in the pan for 5 minutes, then transfer to a wire rack.

Beat softened butter and cream cheese, gradually add confectioners' sugar and lemon juice, until creamy.

Frost cooled cupcakes and optionally decorate with blueberries and lemon zest.