First, prepare the bread by laying the slices on a baking sheet in a single layer. Place in the oven on 200°. The idea is to dry out the bread, not toast it. Check periodically for the bread to feel dry and crusty. Flip over and do the same to the other side. Once the bread slices are dried out, remove from oven and set aside. Repeat for the rest of the bread slices. After the bread is all dried out, cut into cubes. DON'T STRESS...THEY DO NOT HAVE TO BE THE EXACT SAME SIZE. This takes a little time, so I usually do all the bread preparation the night before. Once bread is cubed, either set aside and continue with recipe, or if you are making it the night before, place in a ziploc bag.
Preheat oven 350°
Chop celery into small pieces and peel and chop onion.
Add the stick of butter in a large oversized skillet and melt. Add onions and celery. Add half the sage seasoning. Cook until softened.
Once veggies are softened, carefully add bread cubes and combine. CAUTION: the veggies will be HOT so be very careful when mixing. If you can't mix it all in the pan, move to the large foil baking pan we will use later.
Add chicken broth to mixture a little at a time to soften the bread. You want the bread and veggies to be softened like usual stuffing.
Add the rest of sage by sprinkling over stuffing and combine well.
Once bread, veggies, broth, and sage are combined. Place in large foil baking pan. Cover with foil.
Place in oven and bake for 90 minutes. Throughout bake time, periodically baste with more chicken broth (or if you are cooking along with a turkey and have turkey "broth" cooking on the stove from the giblets and neck, then use that liquid. It provides much more flavor than just the broth).