Preheat your oven to 350°F (175°C).
In a large bowl, combine cooked spaghetti, shredded chicken, cream of chicken soup, sour cream, 1 ½ cups of cheddar cheese, and mixed vegetables.
Stir in garlic powder, onion powder, salt, and pepper.
Transfer the mixture into a greased 9x13 inch baking dish and spread it out evenly.
Top with the remaining ½ cup of cheddar cheese.
Bake in your preheated oven for 25-30 minutes, or until bubbly and golden brown on top.
Remove from the oven and let it sit for 5-10 minutes before serving.