Rinse frozen spinach under running water to separate. Drain; pat dry with paper towels.
Preheat oven at 350°. This recipe calls for a 13 x 9 x 2" pan
unprepared; set it aside. To prepare White Sauce, heat margarine in a 1 quart saucepan over low heat until melted. Stir in flour and salt. Cook over low heat, stirring constantly, until bubbly; remove from heat. Stir in milk. Heat to boiling, stirring constantly.
Boil and stir 1 minute; cover and keep warm. If sauce thickens, beat in small amounts of milk. To prepare lasagna noodles, cook them as directed on package directions. In a mixing bowl, combine spinach, cottage cheese, Parmesan cheese, basil, oregano, and pepper; set aside.
In a skillet, cook mushrooms, carrots, onions, and bell peppers until soft and tender; set aside. Arrange 4 noodles in pan. Top with with half cheese mixture, ½ cup mozzarella cheese and 4 more noodles. Layer cooked vegetables on noodles. Spread half of the White Sauce over top. Top with remaining noodles, cheese mixture, White Sauce, and mozzarella cheese. Bake for 45 minutes.
Let stand 10 minutes before cutting.