In a large bowl, combine the cooked chicken, squash, onion, cheese, cream of chicken soup, milk, garlic powder, and dried parsley. Season with salt and pepper, to taste.
Spread the mixture in an even layer in a greased 9x13 inch baking dish.
Bake in preheated oven for 20-25 minutes, or until the cheese is melted and bubbly.
Serve warm.
Interesting Facts
This casserole is a great way to use up leftover cooked chicken.
You can use any type of squash, such as butternut, acorn, or zucchini.
This casserole can be made ahead of time and refrigerated until ready to bake.