Start with the sauce. In a large frying pan, saute the ground beef in the olive oil until it loses its raw, red color, then remove and set aside. In the same pan, saute the sliced mushrooms and chopped onion in the butter until transparent. Return the beef to the frying pan, add all the other sauce ingredients, and cover. Simmer for 20 minutes.
Meanwhile, prepare the lasagne. Presoak yo