1-Preheat oven to 350°F and position the rack in the center. Line 18 muffin cups with paper liners to get ready for baking.

2-Beat softened butter and sugar for 3-5 minutes until light and fluffy, creating a creamy base for your batter.

3-Beat in egg whites one at a time until fully combined, which helps bind the ingredients together nicely.

4-Sift together cake flour, baking powder, and salt, then reserve 1 tablespoon of this mixture for later use.

5-Whisk together milk, sour cream, and vanilla extract in a separate bowl to add moisture and flavor.

6-On low mixer speed, alternately add the dry mixture in 3 parts and the milk mixture in 2 parts, starting and ending with the dry ingredients. Mix for 15-30 seconds until just combined to keep the batter light.

7-Toss blueberries with the reserved 1 tablespoon of dry mix, then fold them gently into the batter to distribute evenly.

8-Divide the batter evenly among the 18 cups, filling each about ¾ full for even rising.

9-Bake for 16-18 minutes until the tops spring back when touched. Let them cool in the pan briefly before transferring to a rack to cool completely.

10-Beat butter and vanilla for 1 minute until smooth, setting up a creamy foundation.

11-On low speed, gradually add powdered sugar, meringue powder, salt, and blueberry powder until combined it might look clumpy at first.

12-Increase speed to medium and whip for 5 minutes, scraping the bowl occasionally, until the mixture becomes light and fluffy.

13-If the frosting is too stiff, add milk 1 tablespoon at a time until you reach the right consistency.

14-Reduce speed to low and mix for 1 minute to remove any large air bubbles for a smooth finish.

15-Pipe the frosting onto cooled cupcakes and top with fresh blueberries for a beautiful presentation.