Baked Ziti with Ricotta

Preheat your oven to 375°F (190°C) and lightly coat a 9x13-inch baking dish with nonstick cooking spray. Bring a large pot of salted water to a boil and cook the ziti according to package directions until al dente, then drain well.
While the pasta cooks, heat the olive oil in a large skillet over medium heat. Add the chopped onion and cook for 4-5 minutes until softened, then add the minced garlic and cook for 1 more minute until fragrant.
Add the ground beef to the skillet, breaking it up with a spoon, and cook until no pink remains, about 7-8 minutes. Stir in the marinara sauce, bring to a simmer, then remove from the heat.
In a medium bowl, combine the ricotta cheese, 1 1/2 cups of the shredded mozzarella, Parmesan cheese, beaten egg, parsley, salt, and pepper. Mix until well combined.
Add the drained ziti to the skillet with the meat sauce and stir to coat evenly. Transfer half of the sauced pasta to the prepared baking dish. Spread the entire ricotta cheese mixture evenly over the pasta layer. Top with the remaining sauced pasta.
Sprinkle the remaining 1/2 cup of mozzarella cheese over the top. Bake for 25-30 minutes, or until the cheese is melted and bubbly and the edges are lightly browned.