Get a head start by making the corn bread a day or two ahead.
Preheat oven to 375°.
Combine first 3 ingredients in a large bowl. Combine the broth, celery, onion, and butter in a large saucepan; bring to a boil. Reduce heat, and simmer 10 minutes. Add broth mixture to corn bread mixture, stirring well. Add sage and next 4 ingredients (sage through egg white); stir well to combine.
Pour the mixture into an 11 x 7-inch baking dish coated with cooking spray. Bake at 375° for 45 minutes; cover and bake an additional 30 minutes or until golden.