Prepare all the ingredients into a dough.
Roll out the dough on a floured work surface and cut it into rounds (so that it fits into small pie or muffin tins). Spread the molds with dough and prick a few times with a fork.
Rinse broccoli, clean and cut into small roses. Clean and chop mushrooms. Steam a little 3-5 min until soft, then add the broccoli roses for a minute. Mix milk, egg, sour cream or crème fraiche and the grated cheese and season with salt, pepper and a pinch of nutmeg.
Fill each tartlet with a tablespoon of vegetables and pour the milk-cheese sauce over them. Bake in the oven at 175 °C for about 20 minutes (convection oven).