Preheat the oven to 350°. Don’t wrap the sweet potato(es) (though you may want to place a piece of foil or sheet pan under them in case they drip—if they do, it will be the natural sugar in them), but place them right on an oven rack and bake until they are soft all the way through, about 50 to 70 minutes. When they are cool enough to handle, remove the skin and press the meat through a strainer.
In a kitchen mixer equipped with a wire whisk, beat the egg, egg yolks, sugar, and salt until fluffy and lemon colored, then whisk in the milk, cream, vanilla, and 1 cup (or 2 cups if you’re not using Beauregards) of the strained sweet potato, and whisk until thoroughly blended. Divide the mixture among six 4-ounce custard cups. Place the cups in a baking pan large enough to hold them without touching, and add enough hot water to come about half way up the sides of the cups. Bake until the custards are set, about 40 minutes. If they are not completely firm when you remove them from the oven, they will set up as they cool. Serve warm, at room temperature, or chilled.
Copyright© 2000 by Paul Prudhomme