How to cook
Beat egg yolks with sugar until white. Add the flour and beat again. Top with 1/2 cup milk and beat well again.
Place the remaining milk to heat in a pot for about 5 minutes. Add the vanilla stick.
Pour the egg mixture while stirring into the warm but not hot milk and beat with a whisk.
Beat in an eight-pattern with the whisk and stir until thickened. Shortly after the pastry cream boils, it should be ready.