Sort the spinach, wash and drain. Clean and slice the mushrooms. Peel onion and garlic. Chop the onion finely, press the garlic through a garlic press.
Bring the stock to the boil in a pot, add the spinach and cook covered for about 3 minutes until it has collapsed. Cook pasta in boiling salted water according to package instructions until al dente. Heat the oil in a pan and fry the mushrooms, onions and garlic for 7-8 minutes while turning.
Season with salt, pepper and nutmeg. Dust with flour and sweat it. Add spinach with the stock and cream, bring to the boil while stirring. Let the sauce simmer for about 5 minutes. Season to taste with salt and pepper.
Drain the pasta, let it drain and mix with the spinach-mushroom sauce. Serve immediately.