Place squash and onion in a 3-quart casserole dish.

Cover the dish and cook in the microwave until the squash is tender-crisp, about 5 minutes.

Drain any excess liquid from the casserole dish.

In a separate bowl, combine cream of chicken soup and sour cream.

Stir in shredded carrots.

Gently fold the soup mixture into the drained squash and onion.

Combine stuffing mix with melted butter or margarine.

Spread half of the stuffing mixture in a 7 x 11-inch baking dish.

Spoon the vegetable mixture over the stuffing in the baking dish.

Sprinkle the remaining stuffing mixture over the vegetables.

Cook in the microwave for 7 to 10 minutes, or until heated through.