-Method-

Melt the butter and the chocolate in a bain marie and stir until they become homogeneous.

Mix the eggs, the vanilla extract and the sugar in a separate bowl with a mixer, until the eggs get white.

Add the chocolate-butter mixture and mix it all together.

Then, add the flour and keep mixing until all ingredients become homogeneous.

Butter the little oven-safe glass bowls and fill 2/3 of them with the mixture.

Bake them in a preheated oven at 210^oC for 10-14 minutes.