In a large pot, heat olive oil over medium heat. Add beef and turkey, breaking into small bits as it cooks. Cook until meat is browned; drain off fat. Add onion and garlic and cook 2–3 minutes.
Add crushed tomatoes, tomato sauce, tomato paste and water. Mix thoroughly. Add agave syrup, salt and pepper. Simmer 1½ hours, stirring every 10–15 minutes to prevent the bottom from burning.
Preheat oven to 375°F.
Combine ricotta and egg. Mix mozzarella and Parmesan cheese. Reserve ⅓ of cheese mixture for topping. Add grated zucchini and yellow squash to the other ⅔.
In a 9-inch by 13-inch pan, add 1½ cups of sauce, 1 layer of noodles, ½ of the ricotta mixture and ½ of the cheese/veggie mixture. Repeat these layers once more.
Add another layer of 1½ cups of sauce, noodles, 1½ cups sauce and top with reserved mozzarella and Parmesan cheese.
Cover with foil, tenting so that it doesn’t stick to the cheese. Bake covered for 25 minutes; remove foil and bake another 20–30 minutes, or until the top is golden and a little bubbly.