Bring large pot of salted water to boil. Cook spaghetti according to package instructions. Drain and set aside.
While pasta is cooking, cook ground turkey in a large skillet over medium high heat. Drain and add onion. Cook another 5 minutes or until onion has softened. Stir in marinara sauce and salt and pepper.
Combine the eggs, butter and Parmesan cheese in a large bowl. Add cooked pasta and toss to combine.
Spray a 9x13 dish with non-stick cooking spray. Add half of the spaghetti mixture to the dish. Follow with half of the cottage cheese, half of the meat sauce, and half of the mozzarella cheese. Repeat layers. Cook for 40 minutes, covered. Remove foil and cook another 10 minutes. Add fresh chopped basil prior to serving.