Preheat oven to 350 degrees. Line cupcakes tins with paper liners.

Whisk flour, baking powder,salt, and baking soda in a medium bowl.

In another bowl, beat butter on medium-high for 30 seconds.

Add sugar and vanilla to the butter, beat until combined.

Add egg whites and eggs, one at a time, beating well after each one is added.

Alternate the flour and buttermilk mixture, beating on low speed until everything is mixed together.

Scoop the batter into the lined cupcake tins until they are ⅔ rds filled.

Bake at 350 for 20-25 minutes or until a toothpick inserted in the center comes out clean.

Remove from oven and allow to cool for 10 minutes.

Remove from cupcake tray and place on wire racks allowing to cool completely.

Using a small spoon or a cupcake scoop make a small hole in the center of each cupcake. Don't make the hole completely through the cupcake bottom

Fill the hole in the cupcake to the top of the baked and cooled cupcake with the blueberry filling.

Cream the butter and powder sugar until it looks light and creamy.

If it doesn't cream add several drops of the heavy whipping cream until it creams.

Test to see if the frosting can form and hold a stiff peak by taking a spoonful of frosting and turning the spoon upside down. If the frosting stays on the spoon it is ready if not then....

Add more powder sugar ½ C at a time.... mix well.

Test to make sure that the frosting can make and hold a stiff peak.

If ready scoop the frosting into a pastry bag with a large tip.

Twist the open end of the pastry bag to push the frosting to the #15 tip.

Start by frosting on the outside edge of the cupcake working to the center of the cupcake.