Preparation Steps

• In a small bowl, whisk together the egg whites, 1/4 cup of the whole milk, and the lemon zest. Set aside.
• In a mixing bowl, beat the softened butter and granulated sugar until creamy, about 2-3 minutes. Add the dry ingredients (cake flour, baking powder, salt) and mix until just combined. Slowly add the egg white mixture and beat until incorporated. Beat in the remaining milk.
• Prepare cupcake tins with paper liners. Fill liners about half full. Bake in a preheated oven at 350°F (175°C) for 15 minutes. Remove from oven and let cool in the pans for 5 minutes before transferring to a wire rack to cool completely.
• For the frosting: In a mixing bowl, beat the softened butter for 3-5 minutes until pale in color. Gradually add the powdered sugar, lemon zest, lemon juice (about 2 Tablespoons from a fresh lemon), and heavy cream. Beat for another 3-5 minutes until light and fluffy.
• Once the cupcakes are completely cool, frost them using a piping bag with your desired tip, or a spatula.