Preheat the oven to 350 degrees . Line cupcake pans with paper liners, then lightly coat liners with cooking spray. In a large bowl, whisk flour, sugar, baking powder and salt. Using an electric mixer, gradually beat in the butter on low speed (mixture will look sandy). Add the egg (mixture will look crumbly). Add the egg whites 1 at a time, beating to blend between additions. Beat in milk in two additions, then vanilla. Divide batter among liners.
Bake cupcakes until a toothpick inserted into the centers comes out clean, about 10 minutes for mini cupcakes and 22 minutes for standard cupcakes. Let cool completely.
In a medium bowl, using an electric mixer, beat the cream cheese and butter to blend on medium speed. Gradually mix in the confectioners' sugar, then the food color. Frost cupcakes, then decorate with sprinkles.