Preheat oven to 375°. Sauté frozen onion mixture and garlic in 1 Tbsp. hot oil in a large, deep skillet over medium-high heat 2 minutes or until vegetables are tender.
Stir in squash, next 5 ingredients, 1 tsp. Creole seasoning, and 1/4 cup water. Cover, reduce heat to medium, and cook, stirring occasionally, 15 minutes or until squash and potatoes are tender. Stir in 1 can chicken broth.
Remove from heat; cool 15 minutes. Stir together stuffing mix, egg, and remaining 1 can chicken broth and 1 tsp. Creole seasoning in a medium bowl. Fold into cooled squash mixture. Spoon mixture into a lightly greased 13- x 9-inch baking dish.
Bake, covered with aluminum foil, at 375° for 25 minutes. Uncover and sprinkle with pecans; bake 20 minutes or until dressing is thoroughly heated and pecans are toasted. Let stand 10 minutes before serving. Garnish, if desired.