Makes 6 servings.
1 ½ cups heavy cream
6 tablespoons dark muscovado sugar
¼ teaspoon salt
6 tablespoons water
2 tablespoons Demerara sugar
4 large egg yolks
½ teaspoon vanilla
Accompaniments: whipped cream, chocolate shavings.
6 4-ounce ramekins
Put oven rack in middle position and preheat oven to 300° F.
Bring cream, muscovado sugar, and salt just to a simmer in a small heavy saucepan over moderate heat, stirring until sugar is dissolved.
Bring water and Demerara sugar to a boil in a 2-quart heavy saucepan over moderate heat, stirring until sugar is dissolved. Continue to cook, stirring occasionally, until browned and bubbly, about 5 minutes. Remove from heat and carefully add cream mixture (mixture will bubble up and steam), whisking until combined.
Whisk together yolks and vanilla in a large bowl, then add hot cream mixture in a stream, whisking. Pour custard through a fine-mesh sieve into a 1-quart glass measure. Skim off any foam with a spoon.
Divide custard among ramekins. Arrange ramekins in a small roasting pan and bake in a hot water bath, uncovered, until custards are set around edges but still tremble slightly in centers, about 40 minutes. Transfer ramekins to a rack with tongs and cool to warm or room temperature. Pots de creme will continue to set as they cool.