Slice the mushrooms finely and cut the squid into regular sized rings. Soften the shallot in a pan with oil. Add the squid and then the mushrooms, leave to cook on a high flame. Pour in the white wine and leave to evaporate. Add the cream and season with salt, pepper and fresh oregano leaves. Cook the pasta in plenty of boiling, salted water. Drain quickly, retaining a little of the cooking water. Sauté in a pan with the sauce and leave to blend together well. Serve hot and sprinkle with finely chopped oregano leaves to taste.