Clean, wash and slice the mushrooms. Peel the onion and cut into cubes. Heat some butter in a saucepan and sauté the onions in it. Add the mushrooms and sauté briefly. Top up with meat stock and cream and season with salt and pepper.
Cook the tortellini according to the instructions and place in an ovenproof dish. Pour the mushroom sauce over them. Sprinkle the grated Gouda and Parmesan on top and bake in the oven at 180 ° C top heat until golden yellow. Garnish as desired.