Preheat oven to 350°F (175°C).
Cook the penne pasta in a large pot of salted boiling water according to package instructions until al dente. Drain and set aside.
Heat olive oil in a large skillet over medium heat. Add chopped onion and cook for 3-4 minutes until softened.
Add minced garlic and cook for 1 minute until fragrant.
Add ground beef to the skillet and cook until browned, breaking it up with a spoon, about 6-8 minutes. Drain excess fat.
Stir in marinara sauce, dried Italian seasoning, salt, and black pepper. Simmer for 5 minutes.
In a large mixing bowl, combine cooked pasta and meat sauce mixture. Mix well.
Lightly grease a 9×13-inch baking dish. Spread half of the pasta mixture evenly in the dish.
Sprinkle 1 cup of shredded mozzarella cheese over the pasta layer.
Add the remaining pasta mixture on top and sprinkle with the remaining 1 cup of mozzarella cheese and grated Parmesan cheese.
Cover the baking dish tightly with aluminum foil. If freezing, wrap the dish in plastic wrap or place in a freezer-safe container and freeze for up to 3 months.
To bake from frozen, preheat oven to 375°F (190°C). Remove plastic wrap and keep foil on. Bake covered for 50-60 minutes until heated through and bubbly.
Remove foil and bake an additional 5-10 minutes until cheese is golden and melted.
Garnish with chopped fresh parsley before serving.