Boil the chicken breasts in a pan until cooked through. (Save the water after boiling.)
Shred the chicken breasts. This is quick and easy to do in a stand mixer with the paddle attachment.
Prepare the Jiffy Cornbread according to the package directions or make a pan of cornbread from your favorite recipe.
Crumble the cornbread and put it in a large mixing bowl. Add the shredded chicken, chopped onion and celery, crumbled white bread, sage, salt and pepper.
Lightly beat the eggs and then add to the mixture in the bowl. Add the cream. Mix all of the ingredients well.
Add about ½ cup of the cooled chicken broth and begin to mix. Add more chicken broth (¼ cup at a time) until the mixture plops back into the bowl in clumps when you drop it from your hand. The mixture should not have so much broth in it that it runs off your hand!
Butter a 9x13 pan and pour the mixture into the pan. Bake at 475 F for 35 to 35 minutes or until the center is set.