3/4 cup whipping cream
 2 tablespoons unsalted butter, cut into 2 pieces
 12 ounces semisweet chocolate chips or semisweet chocolate, chopped
 1 teaspoon vanilla extract
 Put the cream and butter in a medium saucepan and heat over medium-low
 heat until the cream is hot and the butter is melted.  The hot cream
 mixture will form tiny bubbles and measure about 175 F on a food thermometer.
 Do not let the mixture boil.  Remove the pan from the heat.  Add the chocolate
 and let it melt in the hot cream mixture for about 30 seconds to soften.
 Add the vanilla and stir the sauce until it is smooth and all of the chocolate
 is melted.
 To Freeze:  Pour 1 cup of the sauce into each of 2 plastic freezer containers,
 leaving 1 inch of space at the top.  Loosely cover and cool for 1 hour at
 room temperature.  Press a piece of plastic wrap onto the top of the sauce
 and cover the container tightly.  Freeze up to 2 months.
 To Serve:  Remove from the freezer.  Defrost in the covered container
 overnight in the refrigerator.  Warm the sauce in a medium saucepan over
 low heat, stirring frequently.  Leftover sauce can be stored up to 2
 weeks in the refrigerator.