Cut the mushrooms into slices and wash them quickly. Peel and finely dice onions and garlic.
Heat the oil and fry the onions, garlic and mushrooms in it. Deglaze with cream, bring to the boil and simmer for a few minutes. Finally, melt the cream cheese in it and season with salt and pepper. Quarter the tomatoes and add them.
Sprinkle the basil leaves and freshly grated parmesan on top and serve with the spaghetti.