Clean and wash the spring onions and cut into fine rings. Peel and finely dice the onion. Clean and quarter the mushrooms.
Cook the spaghetti al dente.
Heat the butter and briefly toast the diced onions in it. Add the mushrooms and fry for about 2 minutes. Deglaze with the vegetable stock and stir in the cream cheese. Let the ragout cook for 5 minutes.
Rinse the thyme, put a few twigs aside, pluck the leaves from the rest and chop. Stir into the ragout with the spring onions and season to taste with salt and pepper.
Drain the spaghetti, arrange on plates and pour the mushroom sauce on top. Garnish with the remaining thyme sprigs and serve with grated Parmesan.