1-Preheat the oven to 350°F (175°C). Line cupcake pans with paper liners.

2-In a bowl, whisk together flour, baking powder, baking soda (if used), and salt.

3-In a separate large bowl, cream together softened butter and sugar with lemon zest until light and fluffy.

4-Add eggs one at a time (or both eggs and yolk), mixing well after each addition, then add vanilla extract.

5-Alternately add the dry ingredient mixture and milk/lemon juice mixture in batches, mixing gently and just until combined to avoid overmixing.

6-Toss the blueberries with a tablespoon of flour, then gently fold them into the batter to prevent sinking.

7-Fill cupcake liners about two-thirds full (or 3/4 full) and bake for 16 to 21 minutes depending on cupcake size check doneness with a toothpick. Mini cupcakes bake for about 11 to 13 minutes.

8-Cool cupcakes in the pan for a few minutes, then transfer to a wire rack to cool completely before frosting.

9-Beat cream cheese and butter together until smooth and creamy.

10-Gradually add confectioners’ sugar and lemon juice, beating until light and fluffy.

11-Mix in vanilla extract, optional lemon extract, lemon zest, and a pinch of salt.

12-If frosting is too thick, add a teaspoon of milk or heavy cream to reach desired consistency.

13-Frost cooled cupcakes with a spatula or pipe frosting using a piping bag and large tip.

14-Garnish with lemon slices and extra blueberries if desired.

15-Refrigerate frosted cupcakes uncovered for about 20 minutes before serving to help set the frosting.