Grease ten ovenproof cups (each containing approx. 225 ml) and place them on a baking tray. Cream 250 g butter, sugar and vanilla sugar with the whisks of the mixer. Stir in the eggs one by one. Add 100 g "Nutella". Mix flour, baking powder and cocoa, stir into the dough with 200 g cream.
Pour the dough into the piping bag and cut off a large tip. Pour dough approx. 3⁄4 high into the cups. Bake the cakes in a preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer) for 25-35 minutes (stick test). Remove and let cool down.
Slightly warm 50 g of "Nutella" while stirring. Whip 150 g cream until stiff and spread it on the cupcakes as a topping. Decorate with liquid "Nutella". Serve the cakes in the cups.
TIP for decorating: Spill liquid nut nougat cream on the cream topping and then, preferably with a wooden skewer, intertwine them like marble.
Ovenproof? Porcelain and ceramic cups are fired at around 1000 °C and should withstand the baking temperature of 175 °C. If this is too delicate for you, you can also bake the cakes in preserving jars, small soufflé cups or a muffin tray.