No bain marie or torches here... just a slow cooker and your broiler. Adapted from "Make It Fast, Cook It Slow" by Stephanie O'Dea, as published by Caroline Russock at Serious Eats http://bit.ly/9344mk
Place a 1 1/2 qt heat-proof dish (or 4 6-ounce ramekins) in a 6 qt slow cooker. Add hot water to come 3/4 of the way up the sides.
Whip together cream, egg yolk, sugar and vanilla. Pour into dish (or divide equally into ramekins). Cover the slow cooker and cook on high 2-4 hours. The edges should be set, but the center of the custards should still be jiggly. It is much harder to overcook these in the slow cooker than the oven, so don't worry.
VERY CAREFULLY remove the baking dish/ramekins (use oven mitts! ramekins can be removed with tongs; wrap rubberbands around the tips to provide friction and prevent slips). Allow to cool completely on the countertop, then refrigerate 3-4 hours until very cold.
Spread sugar evenly over the top(s) and brown with a hand torch, or place as close as possible to the broiler element of your oven for 3-5 minutes. Cool briefly and refrigerate until ready to serve.