This is the best hot chocolate sauce I've ever tasted. It can transform the simplest dessert into a grand finale.
1 cup heavy cream
8 tablespoons (1 stick) unsalted butter, cut into pieces
8 ounces bittersweet or semisweet chocolate, coarsely chopped
In a medium heavy saucepan, combine the cream and butter. Bring to a simmer over moderate heat, stirring to dissolve the butter.
Reduce the heat to low and add the chocolate. Whisk until melted and smooth. Use hot or let cool, then cover and refrigerate for up to 2 weeks before serving. Reheat gently, preferably over simmering water or in a microwave oven, stirring until smooth and warm.