Coarsely chop the peanuts. Cream butter, peanut cream, sugar, vanilla sugar and 1 pinch of salt with the whisks of the mixer. Stir in the eggs one by one. Mix flour, baking soda and peanuts, add to the butter mixture and stir well. Stir in milk. Dice marshmallows (see page 60) very finely and fold into the cookie mixture.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Line a baking tray with baking paper. Using a teaspoon, place 12-15 small piles of dough on the baking tray. Leave space in between, as the dough will run during baking. Bake in a hot oven for about 14 minutes.
Remove the baking tray from the oven and place it on a cake rack. Let it rest for about 5 minutes. Remove cookies from the tray and let them cool down on a cake rack. In the meantime, bake 20-23 more cookies from the remaining dough.