Preheat the oven to 350°F (175°C).
Bring a large pot of salted water to a boil. Cook the frozen cheese tortellini according to the package directions for about 3 minutes. Drain and transfer to a large mixing bowl.
Meanwhile, cook the beef Italian sausage in a skillet over medium heat, breaking it into small crumbles until fully browned. Drain any excess fat.
Add the cooked sausage to the bowl with the tortellini.
Stir in the pasta sauce, Parmesan cheese, garlic powder, oregano, and basil until everything is evenly coated.
Lightly grease an 8×8-inch casserole dish and spread the Italian Sausage Tortellini Casserole mixture evenly inside.
Sprinkle the mozzarella cheese over the top.
Cover with aluminum foil and bake for 20 minutes.
Remove the foil and broil for 2–4 minutes until the cheese is bubbly and lightly golden.
Garnish with chopped parsley before serving.