Add butter and sifted powdered sugar into the bowl of a stand mixer fitted with the whisk attachment. Beat on low to bring ingredients together, then turn to medium and beat until well mixed.
Add 2 tablespoons milk, vanilla, and almond extract. Beat on low until incorporated, then turn to medium-high and beat until frosting is light and fluffy, at least 5 minutes. Add more milk as needed for desired consistency. Spread on cake as desired.
Notes
Makes enough for 1 8- or 9-inch layer cake or 24 cupcakes.