Melt the butter in a large saute pan on medium heat. Add the zucchini and yellow squash and cook until slightly tender, about 4 minutes. Add the mushrooms and cook for about 3 minutes. Add the spinach and turn off the heat. Toss to combine, letting the spinach wilt. Season with salt and pepper.
Spray a 9-by-13-by-2-inch baking dish with cooking spray. Place 3 lasagna noodles on the bottom of the baking dish, forming 1 layer (the noodles may overlap). Layer one-third of the veggie mixture, one-third of the ricotta cheese and one-third of the Cherry Tomato Sauce in the dish, spreading each layer evenly. Top with 1/2 cup of the basil. Repeat a second time with the noodles, veggie mixture, ricotta and tomato sauce; top with the remaining 1/2 cup basil. Repeat a third time, but finish the top layer with the mozzarella.
Cover with aluminum foil and bake for 35 minutes. Remove the aluminum foil, turn the oven to broil and broil on high until the cheese is crisp and golden, about 5 minutes.
Cherry Tomato Sauce:
Preheat the oven to 350 degrees F.
Combine the tomatoes, oregano, thyme, parsley, olive oil, garlic and onions on a large baking sheet. Season with salt and pepper and toss, making sure everything is evenly coated. Bake until the tomatoes are golden and the onions are caramelized, about 20 minutes.
Carefully peel the garlic, making sure not to burn your fingers. Transfer the ingredients to a blender and process until smooth. Check for seasoning and add more salt and pepper if desired. Reserve for later use.