Heat until just melted, 3 tablespoons butter with 1/3 cup milk. Sift together a mixture of 3 1/2 cups confectioners' sugar, 1/2 cup cocoa, and 1/8 teaspoon salt. Add about 1/2 of this mixture and beat until smooth. Stir in the remaining dry mixture in two portions. Add 1 1/2 teaspoons vanilla. Beat until smooth.

NOTE: If frosting is toothpick to spread easily - beat in 1/2 teaspoon milk or water at a time. (Very good on a chocolate cake).