Cook the pasta in salted water until al dente, drain and set aside.
Thaw the spinach leaves and cut into small pieces. Cut the mushrooms into slices and fry them with the garlic in a butter and olive oil mixture. Season with salt, pepper and basil and then deglaze with the vegetable stock. Add the spinach together with the crème fraîche and, if necessary, season again with salt and pepper. Then briefly toss the pasta in the sauce and serve with parmesan.