Clean and slice the mushrooms. Peel and finely chop the garlic and onion. Heat the oil in a large pan, sauté the mushrooms and then the onion and garlic.
Season with salt, paprika, pepper and rosemary. Stir in the tomato purée, 900 ml water, vegetable stock cube and cream. Bring to the boil, add the spaghetti to the pan and simmer until al dente. Stir occasionally.
Season to taste and serve sprinkled with parmesan.