2 tablespoons olive oil
1/2  onion, chopped
1 teaspoon minced garlic
6  large tomatoes, chopped
1 teaspoon dried oregano
2 teaspoons dried basil
1/4 teaspoon ground pepper
6  lasagna noodles, cooked
1  zucchini, dried
8 to 9  mushrooms, diced
3 cups well-washed fresh spinach leaves
2 cups ricotta cheese
2 cups grated low-fat mozzarella cheese
3/4 cup freshly grated Parmesan cheese

Preheat the oven to 350 degrees.

In a large skillet, heat 1 tablespoon of the olive oil over medium heat. Add the onion and garlic and sauté for 5 minutes, stirring frequently. Pureé the tomatoes in a food processor. Add the tomatoes to the skillet with the onion. Add the oregano, basil, and pepper and simmer for 15 minutes.

Coat a 13x9-inch glass pan with the remaining tablespoon of olive oil. Spoon out enough tomato sauce to cover the bottom of the pan. Put a layer of 3 noodles over the sauce, then layer with half the zucchini, mushrooms, and spinach, and half the cheeses. Repeat, then cover with remaining tomato sauce. Bake until heated through, about 40 minutes. Serve immediately.