Bring a large pot of salted water to a boil. Add the rigatoni and cook until al dente, about 1-2 minutes less than package instructions. Drain and toss with olive oil. Set aside.
In a mixing bowl, combine cooked shredded chicken, ricotta cheese, grated Parmesan, garlic powder, salt, black pepper, and Italian seasoning. Mix well.
Carefully stuff each rigatoni tube with the chicken and cheese filling. Place upright in a greased baking dish, snugly side by side.
In a skillet over medium heat, warm heavy cream until it simmers gently. Stir in additional Parmesan if desired and season lightly with salt and pepper. Pour sauce evenly over stuffed rigatoni.
Sprinkle shredded mozzarella cheese over the top. Cover with aluminum foil and bake at 375°F (190°C) for 20 minutes. Remove foil and bake an additional 10 minutes until cheese is bubbly and golden.
Remove from oven and let cool for a few minutes. Garnish with chopped fresh parsley. Serve warm and enjoy!