Pots de creme are very rich, very thick custards. There is nothing here but vanilla, eggs, and cream, so use the very best you can find. Adapted from a recipe by Kerry Saretsky at Serious Eats. http://bit.ly/hXBXaw
Preheat oven to 300°F Bring a kettle of water to a boil.
Heat the cream in a small saucepan over medium heat. Split the vanilla bean in half lengthwise and scrape out the sticky seeds inside. Add the seeds and the shell to the cream. Heat until small bubbles form around the edge of the saucepan.
Meanwhile, beat the egg yolks and sugar with an electric hand mixer on medium-high speed until pale and light, about 2 minutes.
Add the vanilla extract to the hot cream. Remove and discard the shell of the vanilla bean. Whisking constantly, drizzle the hot cream into the egg yolks.
Divide the custard among 4 ramekins. Place ramekins into a square baking dish. Pull out the rack of the oven and set the baking dish on it. Pour boiling water into baking dish until it comes halfway up the sides of the ramekins. Carefully slide the rack back into the oven and close the door; bake 30 minutes, until the center of each ramekin is barely set and wiggles slightly when shaken.
Carefully move the baking dish to a rack and allow custards to cool to room temperature in the water bath. Cover each ramekin with plastic rap and refrigerate overnight. Serve cold with a dollop of barely-sweetened whipped cream.