Preheat oven to 350.
Saute onion, celery and garlic in some butter (additional to 3 tbsp listed) until soft. About 5 minutes.
Pour stuffing mix, egg, veggie mix and chicken broth into greased casserole dish and mix well. Drizzle melted butter over top.
Cook 30 minutes covered with foil. Uncover and bake another 10 minutes to brown top. Watch it so it doesn't burn.
Enjoy!