Preheat oven to 350 degrees and line cupcake pan with liners. Set aside.
In a medium bowl, whisk (or sift) together the dry ingredients: cake flour, baking powder, and salt. Set aside.
In a large bowl, cream together butter and granulated sugar. Add vanilla and beat until incorporated. Then, add egg whites and beat until light and fluffy, about a minute.
Add flour mixture to butter mixture in thirds, alternating with the milk, just until each ingredient is incorporated and batter is smooth. Do not overmix.
Divide batter between 15 cupcake liners, filling each about 2/3 full. Bake in preheated oven for 16-18 minutes, or until a toothpick comes out clean.
Remove pan from oven and allow to cool for 5 minutes before transferring cupcakes to a wire rack to finish cooling.
Whipped Buttercream Frosting
In a large bowl, add room temperature butter and beat until creamy, about 1 minute.
Add confectioner's sugar and slowly mix until ingredients are fully combined. Then, whip at high speed for 2-3 minutes, or until light and fluffy.
Add vanilla extract, salt, and heavy cream and whip for an additional 3-4 minutes, or until light and fluffy. Add additional heavy cream as needed to reach desired consistency.
Pipe or spread frosting with a knife onto cupcakes and serve.
Frosting will make enough to frost about 16 cupcakes with high, dramatic piped frosting, or 24 cupcakes spread with a knife, a 9x13 sheet cake, or an 8-9 inch two layer cake.
Butter melts around 90 to 95 degrees, and so will your frosting. If your location is nearing this temperature, I'd recommend refrigerating your baked goods until an hour before you're ready to serve them. Refrigerating your frosted baked goods will not hurt them, but you will want to give them some time to come to room temperature before serving.
Optionally, add 1/4 teaspoon of almond extract to your cupcakes and/or buttercream frosting for an elevated, light almond flavor.
For the buttercream frosting, heavy whipping cream can not be substituted with milk, milk will not whip up into whipped cream.