Preheat the oven to 350° F.
Put the egg yolks in a large bowl, preferably with a spout like a pitcher). Add sugar and vanilla and whisk well until sugar is almost dissolved into egg yolks. Slowly add heavy cream, whisking continuously.
Place ramekins in larger pan, such as a roasting pan. Pour the custard mixture evenly among the ramekins, adding other flavorings as desired (see post above).
Open the oven door and slide out the middle rack. Place the roasting pan with the custards on the rack and remove one. Slowly and carefully add hot tap water to roasting pan in the spot where you removed the one ramekin. Replace that ramekin, cover the roasting pan lightly with foil, and carefully slide the rack back into the oven.
Bake for 40 minutes. Give the pan a gentle shake. The center of each custard should still be jiggly. If you used shallow ramekins, most likely they will be done at this point. If your ramekins are deeper and the entire custard is jiggly, put them back in the oven for another 10 minutes. Keep checking at 10-minute intervals until only the centers jiggle. It's better to undercook crème brûlée than overcook it.
Remove from the oven and let the custards cool in the water for 10 minutes. Remove them from the water and place in the refrigerator, uncovered, for at least 4 hours, but up to 2 days.
To caramelize the tops, sprinkle evenly with granulated sugar and use a kitchen torch to caramelize. If you don't have a blow torch, place the ramekins under the broiler until golden brown.