Cook lasagna in a large quantity of boiling water until just barely
tender; drain off most of water; add ice cubes to stop cooking.
(Allow lasagna to stand in cold water to prevent pasta sticking
together.) In a saucepan, brown meat with onion and garlic; drain
off fat. Cook over low heat, covered, for about 5 minutes. Stir in
mushrooms with liquid, tomato sauce, tomato paste, salt, and
oregano. Simmer 15 minutes. Combine egg with spinach, cottage
cheese, and parmesan. Spread 1/3 of meat sauce in 13x9" baking
dish. Cover 1/4 of lasagna (about 5 overlapping strips.) Alternate
another 1/3 of sauce and 1/4 of lasagna. Spread spinach mixture
over pasta and cover with 1/4 lasagna strips. Top with remaining
sauce and pasta. Arrange mozzarella cheese on top. Bake at 350 F
for 30 minutes. Let stand 10 minutes before serving.
