Prepare 2 different bowls: in one you will put all the liquid ingredients (milk, oil and eggs), in the other the dry ones (flour, sugar, cocoa, yeast.
Mix the ingredients separately in the two bowls, then combine the liquid ingredients with the dry ones and mix quickly.
Divide the mixture into the molds lined with baking cups (or buttered and floured), filling them to within 1-2 cm of the edge.
Cook for about 20 minutes in a fan oven preheated to 180°C, then remove from the oven and leave to cool.
Once cool, remove from the mold; then, with the help of a knife and a little caution, cut the central part of the muffin, so that 1 teaspoon of jam can fit inside.
Place the jam, then close with the top of the removed piece of muffin.
Then melt the chopped chocolate (in the microwave or in a bain-marie) and use it to cover the top of the muffin, then leave to dry.
Here you go, your sacher muffins are ready and all you have to do is enjoy them!