1/2 cup (1 stick) unsalted butter, room temperature
1/2 cup solid vegetable shortening
3 1/2 cups confectioners' sugar
1 tablespoon pure vanilla extract
In the bowl of an electric mixer fitted with the paddle attachment, cream butter and shortening until well combined. With mixer on low speed, gradually add the confectioners' sugar, and continue beating until light and fluffy, about 2 minutes. Add the vanilla, and beat to combine. Set aside at room temperature until ready to use.