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

In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until evenly combined.

In a separate large bowl, cream the softened unsalted butter and granulated sugar with a mixer until light and fluffy, about 2–3 minutes.

Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract, lemon zest, and fresh lemon juice until combined.

Alternate adding the flour mixture and buttermilk to the batter, beginning and ending with the flour. Fold gently to combine.

Gently fold in the fresh blueberries until evenly distributed. Divide the batter evenly among the cupcake liners, filling each about two-thirds full.

Bake for 18–20 minutes, or until a toothpick inserted in the center comes out clean. Remove from oven and cool completely before frosting.

For the lemon cream cheese buttercream, beat together equal parts cream cheese and butter, add powdered sugar to taste, plus lemon juice and zest. Beat until smooth and fluffy, then frost cooled cupcakes.