This rich, smooth chocolate sauce is perfect slathered warm over ice cream.
In a heavy small saucepan, melt butter and chocolate over low heat.
Remove from heat; add powdered sugar. Gradually stir in evaporated milk. Bring just to boiling; reduce heat. Boil gently over low heat for 8 minutes, stirring frequently. Remove from heat.
Stir in vanilla. Cool slightly. Serve warm over ice cream. Chill leftovers, covered, up to 1 week. Warm over low heat before serving.