Loaded with 7 vegetables, this is the BEST Vegetarian Lasagna recipe!
Preheat oven to 350F. In a small bowl combine the mozzarella and sharp cheddar cheese. Set aside. Add 1 tablespoon of oil to a large cast iron pot. Add in spinach and cook until wilted.
Add cooked spinach to a large bowl with ricotta, egg, parmesan cheese, garlic powder, onion powder, nutmeg, Italian seasoning, 1/2 tsp salt and 1/2 tsp pepper.
Add the remaining tablespoon of oil and butter to the same pan the spinach was cooked in. Add in mushrooms and cook over medium high heat until golden brown.
Add in carrots, celery and onion to the skillet. Cook for 3-4 minutes or until the vegetables are golden brown. Stir in garlic and cook for an additional minute.
Pour in crushed tomatoes, tomato sauce, Italian seasoning and sugar. Stir to combine and simmer for 10 minutes. Season with salt and pepper to taste.
Ladle 1/2 cup of the tomato sauce on the bottom of a casserole dish.
In this order layer: 3 lasagna noodles, 1/3 of the ricotta cheese, 1/3 of the shredded cheese, and 1/4 of the sauce. Repeat with all of the sauce, noodles, and top with the remaining cheese.
Bake for 40-45 minutes or until the lasagna is bubbling and golden brown on top. If it is starting to get to brown cover with foil.
Allow lasagna to cool for at least 20 minutes before slicing and serving.