Break the dark chocolate into pieces and melt together with butter and salt in the microwave for 1 - 2 minutes at 600 watts, stirring several times in between. Alternatively, you can melt them in a water bath. Add sugar, flour and the two eggs and mix well.
Place a silicone muffin tin on a wire rack and fill it. If you are using a metal mold, grease it beforehand. Place a piece of milk chocolate in the middle of the dough and press in a little. Bake in the oven (preheated) at 220 ° C top / bottom heat for about 10 minutes.
They taste best lukewarm, as a dessert as well as with coffee.