Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with olive oil or non-stick spray to prevent sticking.

Bring a large pot of salted water to a boil. Add mostaccioli and cook according to the package instructions until al dente, about 8-10 minutes. Drain and set aside.

In a large skillet, heat olive oil over medium heat. Add onion and garlic, sautéing until translucent, about 3-4 minutes. Add ground meat and cook until browned, about 6-8 minutes. Drain excess grease.

Pour the marinara sauce into the skillet with the browned meat. Stir well and let it simmer for 5 minutes. Season with salt and pepper to taste.

In a large mixing bowl, combine the cooked pasta with the meat sauce. Stir in 1 cup of shredded mozzarella and ½ cup of grated Parmesan cheese.

Transfer the pasta mixture into the prepared baking dish. Top with the remaining mozzarella and Parmesan cheese, then sprinkle with Italian seasoning.

Bake in the preheated oven for 25 minutes, or until the cheese is melted, bubbly, and golden brown.

Let the baked mostaccioli rest for a few minutes before serving. Garnish with fresh basil if desired.