Ingredients

3 1/2 cups confectioners' sugar 

1 cup unsweetened cocoa powder 

3/4 cup (1 1/2 sticks) unsalted butter, room temperature 

1/2 cup milk, room temperature 

2 teaspoons pure vanilla extract 

Preparation

Into a medium bowl, sift together sugar and cocoa. Whisk in butter, milk, and vanilla until smooth. If not using immediately, refrigerate, covered, up to 3 days. Bring to room temperature before using.