Preheat the oven to 375F.
Place a pan over medium heat with 2 tbsp of oil. Once hot, add the diced onions and cook for 5 minutes until soft. Add the diced bell peppers and zucchini and cook for another 8-10 minutes until soft but still have a crunch. Add the roasted garlic and stir to combine. Add the dried oregano and chili flakes to taste. Lightly season with salt and black pepper. Add the canned tomatoes and bring just to a boil. Remove from the heat and set aside.
In a mixing bowl, stir together the ricotta cheese and eggs. Lightly season with salt and set aside.
In a 9x13 dish, ladle enough of the sauce to just cover the bottom of the dish. Layer on the lasagna noodles to cover in a single layer. Layer on half of the ricotta mixture and spread it evenly. Spoon 1/3 of the sauce on top and generously add a layer of mozzarella cheese on top. Repeat the layers.
Top the lasagna with cheese and cover the dish with foil. Bake for 45-50 minutes. Remove the foil and let it get golden brown in the oven for another 15 minutes.