Preheat oven to 375°.
Heat oil in a large high-sided skillet and cook onion, stirring occasionally, until softened, 6–7 minutes. add garlic and cook 1 minute. Add turkey and cook, breaking up with a spoon, until no longer pink and cooked through, 4–5 minutes. Add marinara, bring to a boil, reduce heat, and simmer 2–3 minutes. Remove pan from heat and cool slightly.
Cook lasagna noodles according to package instructions.
Combine ricotta, spinach, parsley, egg whites, salt, and pepper in a large bowl.
Coat the bottom of a 14- x 11-inch lasagna pan with 1⁄2 cup sauce. arrange three lasagna noodles on the bottom of the pan. Spread 3⁄4 cup sauce evenly over noodles. Spoon 2⁄3 cup ricotta- spinach mixture evenly on top of sauce. Repeat layers two more times.
Cover top with three noodles and remaining 3⁄4 cup sauce. Sprinkle with mozzarella and parmesan. Cover loosely with foil and bake for 45 minutes. Remove foil and bake 10–15 minutes, until cheese is bubbly. Cut into 9 squares and serve.