Chop the vegetables (bell pepper, zucchini, mushrooms, onion) to make 4 cups total.
Sauté the chopped vegetables in 2 tablespoons of olive oil until softened, about 5-8 minutes.
Make the tomato sauce by sautéing the garlic, red pepper flakes, and oregano in olive oil for 1 minute. Add the tomato paste and cook until slightly darkened. Add the canned tomatoes and simmer for 4-5 minutes.
Soak the lasagna noodles in hot water for 10 minutes to soften.
Mix the ricotta with 2-3 tablespoons of heavy cream (optional).
Grate the Parmesan and mozzarella cheeses and mix them together.
Assemble the lasagna in layers: sauce, noodles, ricotta, vegetables, cheese. Repeat for 4 layers, using ¼ of each ingredient per layer, except for the cheese which uses ⅕ per layer.
Top the final layer with a thin layer of sauce and the remaining cheese.
Bake the lasagna covered with foil for 30 minutes, then remove the foil and bake for 20 more minutes until golden brown on top.
