Preheat oven to 375°F (190°C) and grease a 9x13 inch baking dish.
Boil a large pot of salted water and cook penne pasta until 2 minutes short of al dente; drain.
In a large mixing bowl, combine the marinara sauce, heavy cream, minced garlic, dried oregano, and red pepper flakes.
Fold the cooked pasta and meatballs into the sauce mixture until evenly coated.
Transfer the mixture to the prepared baking dish.
Top evenly with shredded mozzarella and grated parmesan cheese.
Bake for 25 minutes until the sauce is bubbly and the cheese is melted and golden brown.
Let stand for 5 minutes and garnish with fresh parsley before serving.