Combine and melt the butter and chocolate in the top portion of a double boiler over - Not In- boiling water, stirring to blend well. Add the boiling water. Blend thoroughly. Add the sugar and corn syrup. Place over direct heat. Cover. Let the sauce boil readily, but not too furiously, for 3 minutes. Do Not Stir!

For a conventional Hot Fudge Sauce (which does Not harden on Ice Cream), uncover, reduce the heat and simmer 2 more minutes, all without stirring the sauce.

For a Fudge Sauce which Will harden on Ice Cream, continue boiling, uncovered 3 more minutes, without stirring the sauce. Add the vanilla just before serving.

Yields 1 Cup Note: This recipe requires attention to detail, but works quite nicely.