3 sticks (12 ounces) unsalted butter, at room temperature
1 1/2 cups powdered sugar
3/4 cup malted milk powder
1/2 cup whole milk, at room temperature
2 teaspoons vanilla extract
1/4 teaspoon kosher salt
Combine butter and sugar in the bowl of a stand mixer fitter with a paddle attachment, and beat on low speed until sugar is incorporated. Increase speed to medium high and beat until mixture is light and whipped, about 3 minutes. Stop the mixer and scrape down the sides of the bowl and the paddle. Add remaining ingredients and return to low speed until ingredients are incorporated. Increase speed to medium high and continue whipping until frosting is evenly combined and light, about 3 minutes. Use to frost cakes, cupcakes, or cookies.