Just before serving, sprinkle enough granulated sugar on top of the custard to coat. Using a kitchen torch, burn the sugar in a circular motion. You should see the sugar move a bit and bubble. Allow maybe a second or two past that and move to the next area until the entire custard has been completed. Should you not own a torch, place the custards on a baking sheet and place in a boiler, rotating for even browning of the sugar.