Preheat oven to 175°C (350°F) and line a cupcake pan with liners.
Beat butter and sugar until light and fluffy (2–3 minutes).
Add egg whites one at a time, mixing well after each.
Mix in vanilla bean paste and almond extract.
In another bowl, whisk flour, baking powder, baking soda, and salt.
Gradually alternate adding dry ingredients with sour cream and milk on low speed.
Mix briefly on medium speed until smooth.
Fill cupcake liners evenly and bake for 18–22 minutes.
Cool completely on a wire rack.