Slice zucchini as thinly as possible. Spread into a single layer on a clean dish towel and sprinkle liberally with salt. Let stand for 10 minutes. Blot up water with a paper towel.
Line 2 baking pans with parchment paper. Preheat the broiler. Place zucchini slices in a single layer on the pans and drizzle with olive oil. Season with freshly ground black pepper. Broil for 10-20 minutes, flipping slices over once, until zucchini is tender and slightly browned on both sides.
Meanwhile, heat olive oil in a large pot over medium heat. Saute onion and garlic until soft. Add red pepper and cook another 5 minutes. Add spinach and stir until wilted.
Add pasta sauce to pot along with red pepper flakes and salt and pepper to taste. Simmer 10-15 minutes until sauce is slightly thickened.
Lightly beat egg in a small bowl. Stir in ricotta, oregano, and parmesan.
Spray a 9x13 dish with cooking spray. Spread a small amount of sauce into pan and top with a single layer of roasted zucchini. Place 3 noodles on top, followed by half the cheese mixture and 1 cup of mozzarella.
Cover with half the remaining sauce and repeat the layer. Place the remaining sauce on top and sprinkle with 1 cup of mozzarella.
Cover with foil and bake for 45 minutes at 350°F.
Remove foil for last few minutes to brown the cheese a bit. Let stand 10 minutes before serving. Garnish with fresh julienned basil.