Preheat oven to 375°F and line a 12-cup muffin tin with paper liners.

In a large bowl, cream together softened butter and granulated sugar until light and fluffy, about 3-4 minutes.

Beat in eggs one at a time, then mix in vanilla extract and lemon zest until well combined.

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

Alternately add the dry ingredients and milk to the butter mixture, beginning and ending with flour mixture.

Gently fold in the flour-coated blueberries, being careful not to overmix the batter.

Divide batter evenly among prepared muffin cups, filling each about 2/3 full.

Bake for 18-20 minutes or until a toothpick inserted in center comes out clean.

Cool in pan for 5 minutes, then transfer to wire rack to cool completely.

For frosting, beat softened butter until fluffy, gradually add powdered sugar and lemon juice, then pipe onto cooled cupcakes.