Boil pieces of celery until soft. Remove strings. Reserve 2/3 cup of the water the celery was boiled in and keep warm.
Finely dice celery and onion.
Melt butter in pan, sauté onions and celery until soft.
Combine the celery water and chicken broth in a measuring cup, making sure it is hot (heat it up if it’s not).
Add bread cubes to a large bowl/pan, add the salt, pepper, and poultry seasoning. Add the cooked onion/celery mixture and the hot celery water/chicken stock. Stir until the bread is moist. It is better to have the bread too moist than not enough because it will be baked.
Spoon the bread mixture into a small baking dish (such as 7x11-inch for a full batch, 9x13-inch for a double batch). Do not flatten it out – leave little hills and valleys for the turkey juice or gravy to settle into.
Bake covered at 350°F for around 40 minutes, then uncover for the last 20 minutes to brown (cook time total of 1 hour). You may also add gravy to the top intermittently during the baking process, but not the last 20 minutes because you're looking to get that crispy top.