3 ½ cups heavy cream
1 cup whole milk
2 vanilla beans (Tahitian preferred), halved, seeds scraped with the back of a knife
8 large egg yolks
1 large egg
2/3 cup sugar
In a heavy-bottomed sauce pan, combine the cream, milk, vanilla beans and seeds and cook over medium heat until it comes to a simmer. Meanwhile, in a large heat-proof bowl, whisk together the egg yolks, egg, and sugar, until the sugar is dissolved.
Temper the hot cream mixture into the egg mixture by ladling the cream into the eggs slowly, in a thin stream. Add about two cups total in this manner, and then transfer the egg mixture back to the pan. Cook another 5-8 minutes, stirring constantly. Once the mixture thickens slightly (check by seeing if it holds a line on the back of a spoon or rubber spatula), remove from the heat, and strain through a sieve. Cool over an ice bath and use or reserve