Cream sugar, vanilla sugar, salt and butter with the whisk of the hand mixer. Add eggs and buttermilk and stir in. Mix flour, baking powder and baking soda, add to buttermilk mixture and stir in briefly.
Place paper cups in the recesses of the muffin tray. Fill half of the pastry and spread 60 g marshmallows on top. Fill in the rest of the dough. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 20-25 minutes.
Chopping chocolate. Halve 40 g marshmallows, mix with the chocolate and place on the muffins 5 minutes before the end of the baking time. Let the muffins rest in the tray for 5-10 minutes. Then take them out of the muffins and let them cool down on a cake rack.
Dust with icing sugar.