Preheat oven to 350°F (175°C).

Grease a 13x9-inch baking dish.

Combine diced zucchini and onion in a medium saucepan.

Add water to cover the zucchini and onion.

Bring to a boil and boil for 5 minutes.

Drain the zucchini and onion and let cool.

In a large bowl, combine shredded carrots, condensed cream of chicken soup, sour cream, and garlic powder.

Add the cooled zucchini/onion mixture and chopped chicken (or turkey) to the bowl.

Mix all ingredients thoroughly.

Spread the mixture evenly into the prepared baking dish.

To prepare the topping, melt butter in a skillet over medium heat.

Add the chicken flavor stuffing mix (including the seasoning packet) to the melted butter.

Toss the stuffing mix until well coated with butter.

Sprinkle the buttered stuffing mix evenly over the casserole.

If desired, sprinkle shredded cheddar cheese over the stuffing topping.

Bake in the preheated oven for 1 hour, or until the casserole is golden brown and bubbly.