Ingredients

1 pound (4 sticks) unsalted butter, room temperature 

2 one-pound boxes confectioners' sugar, sifted 

1/2 cup milk 

1 tablespoon pure vanilla extract 

1/4 teaspoon salt 

1 tablespoon freshly squeezed lemon juice 

Preparation

Beat butter with electric mixer until light and fluffy. Beat in confectioners’ sugar, 1 cup at a time, until smooth. Add milk, vanilla, salt, and lemon juice; beat until smooth. Refrigerate at least 1 hour.