Combine the sugar and water in a heavy saucepan. Stir until all the sugar is moistened, then place over moderately low heat and cook without stirring. Watch carefully as the sugar liquefies and begins to darken. When the sugar has turned a rich golden brown ? do not let it darken too much ? add the cream all at once, being careful as it may spatter and burn you. The sugar will seize into a clump immediately, but as the cream warms, the sugar will dissolve. Keep stirring patiently with a wooden spoon, scraping up the undissolved caramel on the bottom of the pan, until all the caramel has dissolved and the mixture has turned a pale butterscotch color.

Meanwhile, soak the gelatin leaves in a large bowl of cold water until soft, 4 to 5 minutes. Squeeze gently to remove excess water, then add the gelatin to the warm sweetened cream. Stir until the gelatin melts, about 30 seconds, then strain the mixture through a sieve.

Ladle into six 4- to 5-ounce molds. Cover and refrigerate until firm, several hours or overnight. To unmold, run a knife under hot water until the knife is hot, wipe it dry, then run it around the inside edge of each mold and invert onto individual plates.