Preheat oven to 350°F. Line cupcake tins with paper liners.

In a bowl, whisk together dry ingredients: flour, baking powder, and salt.

In a mixing bowl, cream together butter and sugar until light and fluffy. Add egg whites one at a time, mixing after each addition.

Gradually add dry ingredients to wet mixture. Mix in lemon juice and heavy cream until smooth.

Divide batter evenly into cupcake liners. Bake for 15 minutes or until a toothpick comes out clean.

Allow cupcakes to cool completely before frosting with lemon buttercream.