Molten Chocolate Cakes
For the cake: Slit the vanilla bean lengthwise and scrape out the seeds. Boil the vanilla seeds, vanilla pod and milk in a pot.
Melt the chocolate in a metal bowl over a hot water bath.
Heat the butter in a saucepan. Stir in the flour and cook briefly. Remove the vanilla pod from the milk and pour the hot milk into the pan. Simmer over low heat for 10 minutes, stirring frequently.
Pour the mixture into a bowl and cool slightly. Stir in 2 unbeaten egg whites. Stir in the egg yolks one by one until smooth. Stir in the melted chocolate. Beat the remaining egg whites with sugar until stiff. Whisk about 1/4 of the egg whites into the mixture. Gently fold in the rest.
Grease the ramekins with butter and sprinkle with flour. Pour the mixture into the ramekins so they are 3/4 full. Place the ramekins in a roasting pan filled halfway with hot water. Bake for about 20 minutes at 180°C (approximately 350°F). The center should be fluid.
Serve immediately, dusted with powdered sugar.