How to cook
Melt the butter and chocolate in a water bath. Once cool, add the sugar and vanilla and mix until you get a uniform, creamy mixture.
Stir well and gradually add to the chocolate mixture to form a homogeneous dough. Be sure to get paper muffin cups to put in the muffin tray. Once set up, fill the cups with the mixture up to a maximum of 2/3 of their volume.
Preheat the oven to 356°F (180 °C). Bake them for about 25 minutes. They can be served with ice cream or jam.