Start by heating a large skillet over medium heat. Spray the pan with olive oil spray to prevent sticking. Add the red and yellow bell peppers, zucchini, mushrooms, fennel, red onion, and smashed garlic cloves. Sauté the vegetables for about 8-10 minutes, or until they are tender and slightly caramelized. Stir in the balsamic vinegar, dried oregano, dried basil, kosher salt, and freshly ground black pepper. Remove from heat and set aside.
In a mixing bowl, combine the ricotta cheese, Pecorino Romano or Parmesan cheese, and chopped fresh basil. Mix until well combined and set aside.
Preheat your oven to 375°F (190°C). Lightly spray your 9x13 inch baking dish with olive oil spray. Spread a layer of marinara sauce on the bottom of the dish. Place three sheets of no-boil lasagna noodles over the sauce. Spread half of the ricotta cheese mixture over the noodles, followed by half of the sautéed vegetable mixture. Sprinkle with one cup of shredded mozzarella cheese. Repeat this layering process, starting with another layer of marinara sauce, then noodles, the remaining ricotta mixture, the remaining vegetables, and another cup of mozzarella. Finish with a final layer of noodles topped with the remaining marinara sauce and the last cup of mozzarella cheese.
Cover the baking dish with aluminum foil (to prevent sticking, you can spray the foil with olive oil). Bake in the preheated oven for 30 minutes. Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden brown. Let the lasagna cool for about 10-15 minutes before slicing. This will help the layers set and make serving easier.