Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking dish.

In a large mixing bowl, combine sliced zucchini, chopped onion, and shredded carrots. Season with salt and pepper.

In another bowl, mix cooked cheese tortellini with sour cream and cream of chicken soup until well combined.

In a separate bowl, prepare the stuffing mix by combining it with softened butter, using a fork to blend until moistened.

Pour the cheesy tortellini mixture into the greased baking dish, spreading it evenly across the bottom. Gently incorporate the vegetable mixture into the cheesy base.

Sprinkle the prepared stuffing mixture evenly over the top of the casserole.

Cover the dish with aluminum foil and bake for 25-30 minutes, then remove the foil and bake for an additional 10-15 minutes until golden brown.

Let the casserole cool slightly for about 10 minutes before serving.