Fudge Sauce

1 package (12 ounce) semi-sweet chocolate chips
½ cup butter
1 ½ cup sugar
1 can (12 ounce) evaporated milk

Combine all ingredients in a saucepan and bring mixture to a full boil. Reduce heat and boil gently for about 5 minutes, stirring frequently. Remove from heat. Serve warm over dessert. Cover and chill leftovers.