In a large mixing bowl, combine the cooked spaghetti, shredded chicken, cream of mushroom soup, sour cream, half of the mozzarella cheese, half of the cheddar cheese, garlic powder, and onion powder. Mix well.
Season with salt and pepper to taste.
Transfer the mixture to a greased baking dish.
Sprinkle the remaining mozzarella and cheddar cheese on top.
Bake in the preheated oven for 30 minutes, or until the cheese is melted and bubbly.
Let it cool for a few minutes before serving.
Notes:
Feel free to add some veggies like peas or broccoli for extra nutrition.