From America's Test Kitchen Season 3: Bistro Basics
Crème brûlée is all about the contrast between the crisp sugar crust and the silky custard underneath. But too often the crust is either stingy or rock-hard and the custard is heavy and tasteless. Because crème brûlée requires so few ingredients, we knew that finding just the right technique would be key in creating the quintessential version of this elegant dessert.
The texture of the custard should not be firm but rather soft and supple. The secret, we found, is using eggs yolks—and lots of them—rather than whole eggs. Heavy cream gave the custard a luxurious richness. Sugar, a vanilla bean, and a pinch of salt were the only other additions. Despite instructions in many recipes to use scalded cream, we found that this technique was more likely to result in overcooked custard, so we thought we would leave the ingredients cold. The downside, however, was that we needed heat to extract flavor from the vanilla bean and dissolve the sugar. Our compromise was to heat only half of the cream with the sugar and vanilla bean and add the remaining cream cold, which worked perfectly. For the crust, we used crunchy turbinado sugar, which was easy to spread on the baked and chilled custards. A propane or butane torch worked better than the broiler for caramelizing the sugar, and because the blast of heat inevitably warms the custard beneath the crust, we chilled our crèmes brûlées once more before serving.
Separate the eggs and whisk the yolks after the cream has finished steeping; if left to sit, the surface of the yolks will dry and form a film. A vanilla bean gives custard the deepest flavor, but 2 teaspoons of extract, whisked into the yolks in step 4, can be used instead. The best way to judge doneness is with a digital instant-read thermometer. The custards, especially if baked in shallow fluted dishes, will not be deep enough to provide an accurate reading with a dial-face thermometer. For the caramelized sugar crust, we recommend turbinado or Demerara sugar. Regular granulated sugar will work, too, but use only 1 scant teaspoon on each ramekin or 1 teaspoon on each shallow fluted dish. If you don't own eight individual ramekins, see the related Family Style version.