1. Preheat your oven to 375 F (190 C). Lightly grease a 9×13 inch baking dish with cooking spray to prevent sticking.

2. Bring a large pot of salted water to a boil. Add the refrigerated cheese tortellini and cook according to package directions, usually 2-3 minutes, until al dente. Drain the tortellini thoroughly.

3. In a large mixing bowl, whisk together the jarred alfredo sauce, milk, garlic powder, and black pepper until well combined and smooth.

4. Add the cooked and drained tortellini and the shredded or diced cooked chicken to the bowl with the alfredo sauce mixture. Gently toss everything together until the tortellini and chicken are evenly coated in the creamy sauce.

5. Pour the entire mixture into your prepared 9×13 inch baking dish, spreading it out evenly. Sprinkle the shredded mozzarella cheese generously over the top, followed by the grated Parmesan cheese.

6. Place the baking dish in the preheated oven and bake for 20-25 minutes, or until the cheese is melted, bubbly, and lightly golden brown on top. The sauce should also be heated through and simmering around the edges.

7. Once baked, remove the dish from the oven and let it rest for 5 minutes before serving. If desired, garnish with fresh chopped parsley for a touch of color and freshness.