Steam spinach, just until tender. Press out excess moisture, and chop coarsely.
Heat olive oil in large saute pan and saute mushrooms, onions and garlic over medium high heat until onions are tender, but not browned.
Drain any excess liquid and set aside.
Mix together ricotta cheese, 2/3 cup grated Parmigiano, egg, salt, pepper, dried basil and oregano in a large bowl. Add cooled spinach and mushroom, onion, garlic mixture. Mix well to combine.
Cook lasagna according to package directions. Rinse under cool water and drain thoroughly. Lightly oil a 9 x 13 x 2 inch baking dish.
Preheat oven to 350° F.
Put 4 lasagna strips in bottom of pan, overlapping slightly. Top with 2 cups of the spinach filling. Sprinkle with 1 cup shredded cheese and 1/3 cup Parmesan cheese.
Repeat pasta, filling and cheese layering two more times. Top with remaining 4 lasagna strips. Spread 1 cup tomato sauce over the top. Cover lightly with foil.
Bake in preheated oven, covered, for 45 minutes. Remove foil and bake another 10 - 15 minutes. Let rest for 10 minutes after removing from oven.
Contributor: pat ciesla
more pasta recipes all about lasagna - lots more recipes