In a saucepan, over high heat, whisk the cream together with the sugar and vanilla bean. Bring to a simmer and remove from the heat. In a bowl beat the egg yolks until thick and frothy. Temper the egg yolks by stirring just 1 tablespoon of the sauce into the yolks, then another, then another, until all is incorporated. Turn the egg yolk mixture into the sauce and stir until thoroughly blended. Return the saucepan to low heat and cook 2 to 4 minutes, stirring often to prevent scorching. Remove from the heat. Strain through a fine mesh sieve.