Prepare oven: Preheat oven to 400°F. Coat a 13- x 9-inch baking dish and an 8-inch baking dish with cooking spray.
Cook celery and onions: Melt butter in a large skillet over medium-high heat; add celery and onions, and sauté 5 to 6 minutes or until onions are tender. Stir in sage, and sauté 1 minute.
Mix cornbread dressing: Stir together Cornbread Crumbles and breadcrumbs in a large bowl. Stir in eggs, chicken broth, pepper, and celery mixture, stirring until blended.
Add dressing to baking pans: Divide cornbread mixture between 1 lightly greased 13- x 9-inch baking dish and 1 lightly greased 8-inch square baking dish.
Bake dressing: Bake at 400°F for 45 to 55 minutes or until set and golden brown.
