Cook the pasta according to package instructions. Drain and set aside.
In a large mixing bowl, combine the cooked pasta, spinach, Alfredo sauce, half of the mozzarella cheese, Parmesan cheese, garlic powder, salt, and black pepper. Mix well.
Transfer the mixture to a baking dish. Top with the remaining mozzarella cheese.
Bake in the preheated oven for 20-25 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let it cool for a few minutes before serving.
Notes:
Feel free to add cooked chicken or mushrooms for extra protein and flavor.