In small saucepan, heat cream until bubbles form around edge of pan.
Let cool slightly.
In medium bowl, combine butter, salt, cocoa, vanilla, 1/4 cup hot cream, and 1-1/2 cups sugar.
With portable electric mixer at medium speed, or wooden spoon, beat mixture until smooth.
Gradually add remaining sugar, beating until smooth and fluffy.
If frosting seems too thick to spread, gradually beat in a little more hot cream.
Makes enough to fill and frost an 8-inch or 9-inch two-layer cake.
Note: If frosting is too thin, set in bowl of ice water.
Beat until thick enough to spread.