Clean and clean the mushrooms and, depending on their size, possibly halve or quarter them. Peel garlic and chop finely. Peel and finely chop the onion. Wash the rosemary, shake dry, pluck needles from the stems and chop finely.
Heat the oil in a wide saucepan. Sauté the mushroomsdarin vigorously while turning. Add onion and garlic and fry briefly. Season with salt, pepper and paprika.
Add tomato paste, sweat briefly, deglaze with stock and cream. Add spaghetti, bring to the boil, cook over medium heat for 25-30 minutes. Stir frequently. Season again with salt, pepper and paprika. Peel the parmesan with a peeler to form chips. Garnish pasta with parmesan and basil to taste.