Preheat oven to 375 degrees Fahrenheit (190 degrees Celsius) and lightly grease a 9x13 inch baking dish.
In a large skillet over medium-high heat, brown the ground beef and onions until the meat is no longer pink. Add garlic and cook for 60 seconds. Drain excess fat.
In a medium mixing bowl, combine the cooked meat mixture, ricotta cheese, beaten egg, 1 cup of mozzarella, 0.25 cup of parmesan, parsley, salt, and pepper. Stir until homogeneous.
Spread 0.5 cup of marinara sauce over the bottom of the baking dish to prevent sticking.
Lay cooked lasagna noodles on a flat, clean surface. Spread 3 tablespoons of the cheese and meat mixture evenly over each noodle.
Roll each noodle tightly from one end to the other and place seam-side down in the baking dish.
Pour the remaining marinara sauce over the rolls and sprinkle with the remaining mozzarella and parmesan cheese.
Cover with aluminum foil and bake for 20 minutes. Remove foil and bake for an additional 15 to 20 minutes until cheese is melted and golden.
Allow the dish to rest for 5 minutes before serving for internal temperature stabilization.