In a small, heavy-bottomed saucepan, combine the sugar and water and bring the mixture to a boil, stirring often. Cook, stirring occasionally, until the mixture is a deep caramel color and has the consistency of a thin syrup, 10 to 15 minutes. Remove from the heat. Stir in the cream, return the saucepan to the high heat, and boil the sauce until it regains the consistency of a thick syrup, about 2 minutes. Cool.