Bring the milk to a boil with the vanilla bean and the sugar. Beat the eggs and pour in when the milk is hot. Stir well. Preheat the oven to 350F. Strain the mixture into a lightly buttered earthenware dish and bake for 15 minutes. Lower the heat to 275F. The mixture must not boil and you should not see any small holes appear in the flan. When a inserted knife comes out clean it is cooked. Serve chilled.
