Break the chocolate into smaller pieces and transfer together it with the brown sugar to a glass bowl over saucepan filled with some water over low heat.

Gently melt the chocolate. Stir regularly. Take the pan off the heat once the chocolate is fully melted and add the butter.

Stir well until it is fully incorporated. Pour in the milk.

Let the chocolate cool for 5 minutes. Add the the egg.

Stir again. Sift the flour together with the baking powder and baking soda over the bowl of chocolate. Add a pinch of salt.

Whisk well into a smooth and runny batter. Carefully divide this over muffin tins you filled with paper cups.

Bake the cupcakes in a preheated oven at 338°F (170°C) for 20 minutes. Remove them from the oven and let the cupcakes cool in the muffin tin.