In a 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. Stir in the cream, return the saucepan to the high heat, and boil until it regains the consistency of a thick syrup, about 2 minutes. Remove from the heat and cool completely. Stir in the pecans. The sauce can be refrigerated until ready to use. Allow it to reach room temperature before using.