This is a great ganache-like, fudge sauce. It is thick and needs to be heated to be pourable. If you would like a little thinner sauce, add more cream.
Refrigerate this sauce. To reheat, place in the microwave for 15 to 30 seconds.
5 ounces unsweetened baking chocolate
1/2 cup granulated sugar
2/3 heavy cream
1/4 cup unsalted butter
Place the chocolate, sugar, and cream in a heavy saucepan. Bring to a boil, stirring frequently. Remove from the heat and stir in the butter. Serve warm over ice cream.