Gently whisk together egg yolks and sugar in a bowl. Pour half and half in heavy medium saucepan. Scrape seeds from inside of vanilla bean into saucepan then add the bean itself. Over medium heat, simmer until the mixture almost comes to a boil. Remove from heat. Gradually whisk hot half and half mixture into egg yolk mixture. Return mixture to pan and stir over medium-low heat until it thickens slightly, about 10 minutes. Do not allow mixture to come to a boil! Remove vanilla bean. Refrigerate crème anglaise and serve cold.
Makes about 2 cups.
