Cook the pasta according to package directions until just shy of al dente. Drain well and set aside. Preheat oven to 375°F and lightly grease a 9x13-inch baking dish.

Heat olive oil in a large skillet over medium-high heat. Add diced onion and cook for 3-4 minutes until softened. Add garlic and cook for another 30 seconds. Add ground meat, breaking it up with a wooden spoon, and cook until browned and no longer pink, about 6-8 minutes. Drain excess fat, then stir in marinara sauce and Italian seasoning. Simmer for 5 minutes.

In a medium bowl, combine ricotta cheese, egg, 1 cup of mozzarella, Parmesan, and parsley. Mix until smooth and creamy.

Spread half the cooked pasta in the prepared baking dish. Top with half the meat sauce, then dollop the ricotta mixture over top, spreading gently. Add remaining pasta, then the rest of the meat sauce.

Sprinkle remaining mozzarella evenly over the top. Cover with foil and bake for 25 minutes. Remove foil and bake another 10 minutes until cheese is golden and bubbling. Let rest for 10 minutes before serving.