Prepare cornbread (either homemade or Martha White hot rise mix) and let dry out a day or two.
Cut or tear bread into ½ inch cubes and dry out bread overnight on a baking sheet. Toast on a large baking sheet if you are in a time crunch.
The next day, heat oven to 400 degrees f.
Crumble cornbread into little bits.
Combine cornbread, bread cubes, salt, pepper, sage, finely diced onions and celery in an extra large bowl and mix together.
Add five cups of the broth and stir to combine. Taste and adjust seasonings if needed before adding the eggs.
Whisk eggs and stir them into the cornbread mixture.The cornbread mixture should be very wet in consistency. Add the additional cup of broth if needed.
Pour into a well greased, 10 x 15 inch casserole dish and spread out in pan.
Bake covered, at 400 degrees for 1 hour.
After the elapsed time, uncover and shake the dish. If it jiggles, it is not done. If it is firm, it is done. If it doesn't look set, uncover, and bake for additional time until it is firm but still moist on the inside. This could take 5-20 minutes more depending on how deep your casserole dish is or how dry your bread was in the beginning.