Add plenty of water with a little salt. Cut the mushrooms into not too thin slices. Finely chop the garlic.
Put the mushrooms and garlic in a pan with a little olive oil and fry until the mushrooms are nicely boiled down. Meanwhile, put the pasta in the boiling water and cook according to the instructions on the packet.
Deglaze the mushrooms with cream and a little water. Add vegetable stock, green pepper, sage and salt. Let the whole thing simmer over low heat for about 3 minutes. Tie lightly with the sauce thickener and season with black pepper, cayenne pepper and salt.