1. Bring a large pot of salted water to a boil and cook lasagna noodles according to directions for al dente. Once cooked, space the noodles out on a sheet of aluminum foil to keep them from sticking.
2. Cook the spinach according to the directions on the package. Drain. Dice the mushrooms.
3. In a skillet, brown the ground beef and drain the grease.
4. Preheat the oven to 375.
5. Pour the spaghetti sauce and tomato paste into a bowl. Stir until combined. Add in the mushrooms and stir again.
6. In another bowl, mix together the cottage cheese, eggs, Parmesan cheese, parsley, garlic and crushed red pepper flakes.
7. In a 9x13 baking dish, layer 3-4 noodles on the bottom. Layer in this order: ground beef, tomato mixture, spinach, cottage cheese mixture, 1 cup mozzarella cheese. Repeat.
8. Cover with foil and bake for 30 minutes. Remove the foil and bake for another 5-10 minutes or until the cheese is lightly browned on top. If you like really brown cheese and your broiler is on the top of your oven, switch it to broil and broil for 1 minute.
9. Let cool for 10-15 minutes before serving.