1. Melt butter and dark chocolate together over bain marie. Beat egg and sugar until foamy. Gently add the chocolate mixture to the egg mixture. Add flour.
2. Oil spray your mould. Pipe your mixture inside moulds. Keep in the fridge overnight.
3. Bake at 190°C for 8 to 10 minutes. Unmould straight away after baking. Serve warm with caramel sauce and ice cream.