Preheat the oven to 180°C (350°F).

Melt the dark chocolate and butter together in a mixing bowl.

Stir in the Guinness and sugar until well combined.

Add the eggs one at a time, mixing well after each addition.

Fold in the flour and vanilla extract until just combined.

Pour the mixture into ramekins and place them in a baking dish.

Fill the baking dish with water halfway up the sides of the ramekins.

Bake for 25-30 minutes until the tops are set but the centers are still soft.

Let cool slightly before serving.