Melt butter in small saucepan, over low heat.
Re- move from heat.
Add brown sugar, stirring until smooth.
Over low heat, bring to boiling, stirring; boil, stirring, 1 minute.
Remove from heat.
Add cream; over low heat, return just to boiling.
Remove from heat; let cool to 110F on candy ther- mometer, or until bottom of saucepan feels luke- warm.
With portable electric mixer at medium speed, or wooden spoon, beat in 2 cups confectioners' sugar until frosting is thick.
If frosting seems too thin to spread, gradually beat in a little more confection- ers' sugar.
Add vanilla.
Set in bowl of ice water; beat until frosting is thick enough to spread and barely holds its shape.
Makes enough to frost top and side of an 8-inch or 9-inch two-layer cake; or top of a 13-by-9-by-2-inch cake.