Preheat your oven to 375°F (190°C).

Prepare the chicken by shredding it into bite-sized pieces if using leftover cooked chicken, or cook raw chicken in a skillet over medium heat until no longer pink, about 15-20.

Cook the penne pasta in a large pot of salted boiling water according to package instructions until al dente, about 10-12. Drain and set aside.

In a large mixing bowl, combine the cooked penne pasta, shredded chicken, Alfredo sauce, chicken broth, frozen peas, garlic powder, Italian seasoning, salt, and pepper. Mix until well-coated.

Transfer the mixture into a greased 9x13-inch baking dish, cover with aluminum foil, and bake for 25. Remove the foil, sprinkle mozzarella and Parmesan cheese on top, and bake uncovered for an additional 15 until cheese is melted and bubbly.

Let the casserole cool for about 5 before serving.