Bring the sugar and water to the boil in a small, heavy saucepan. Remove from heat and swirl pan by its handle (never stir!) until sugar has completely dissolved and liquid is clear. Put on a tight-fitting cover and boil over moderately high heat for several minutes. When bubbles are thick, remove cover and boil, swirling pan, until syrup turns a light caramel brown. Let cool to about the same temperature as the heated cream. Pour in the cream: The caramel will lump. Simmer, stirring, for a few minutes to melt caramel and blend it with the cream. Stir in the vanilla. Serve warm or cold. (If too thick, simmer with a little more cream. If too thin, boil it down, stirring.)
Yield: 1 1/2 cups