Chocolate Pithivier

• 225 g (8 oz) unsalted butter, softened
• 225 g (8

First make the crème pâtissière. Place the milk in a saucepan with the vanilla pod and heat gently to boiling point. Whisk together the egg yolks, sugar and flour. Pour on the hot milk and whisk lightly together. Return to the saucepan and gently cook the mixture until it thickens and coats the back of the spoon. Continue cooking until the mixture tastes not in the least bit floury. Pour throug