1 stick unsalted butter
2 c. confectioners' sugar
2/3 c. evaporated milk
6 oz. semi sweet or bittersweet chocolate, broken into pieces (use a better quality chocolate)

Melt the butter with the sugar in the top of a double boiler over simmering water. Stir the mixture until combined well. Add milk and chocolate. Cook over simmering water for 1/2 hour; do NOT stir mixture while cooking. Remove pot from heat and beat the sauce until it's smooth. Lick the spoon! Refrigerate and reheat as needed. (Use double boiler or microwave to reheat.)