Preheat oven to 425°F. Grease 6 custard cups. Melt the chocolates and butter in the microwave. Add the flour and sugar to chocolate mixture. Stir in the eggs and yolks till smooth. Stir in the vanilla and liqueur.
Divide the batter evenly among the custard cups.
Place in the oven and bake for 14 minutes. The edges will be firm but the centers will be runny. Run a knife around the edges to loosen and invert onto desert plate.