For the chocolate sauce, chop the chocolate roughly. Bring 200 ml milk to the boil and melt the chocolate in it. Mix cocoa, starch, 3 tablespoons sugar and 50 ml cold milk and stir into the hot chocolate, bring to the boil briefly.
Let the sauce cool down while stirring occasionally. Mix 1/4 l milk, eggs, 1 tablespoon sugar and flour to a smooth dough. Mix quark, vanillin sugar and 2 tablespoons of sugar. Peel and slice the bananas and stir into the quark cream.
Bake the dough in portions in an oil-coated frying pan (approx. 16 cm Ø) until you have 8 thin crêpes. Fill the crêpes with quark cream and fold them in. Add the chocolate sauce.