Clean the mushrooms and cut into quarters. Peel and finely mince onions and garlic. Heat cooking and frying oil in a large pan and fry the onions and champignons for a few minutes. In the meantime, bring water to the boil, add salt and pour in the pasta. Grate the peel of the lemon and place in the pan. Add the garlic, fry for a few moments and deglaze with 200 ml of water. Stir in cream and ricotta and boil up. Drain the pasta in a sieve and mix with the sauce in the pan. Stir and season to taste with salt and pepper.Drizzle each portion with one teaspoon beechnut oil right before serving. Garnish with grated parmesan and a twig of oregano.