Preheat oven to 350℉
Add your chicken stock, chicken base and roasted garlic to your 2 Qt sauce pan and bring to a light simmer
In your 6 Qt pot, add 4 Tbsp of your butter, your celery and your onions and place over medium heat. Add a hefty pinch of salt and sweat until tender and your onions are translucent.
Add in your dried spices and toast lightly until nice and fragrant.
Start adding your bread to your pot. You will probably have to do this in two batches, which is fine. After you've added about half your bread, mix around to coat in the butter and spices. Add about a ladle or so worth of stock and mix gently until you have enough room for the rest of the bread. Add the rest and continue to add in your stock and mix gently so you don't over work it and make it gummy.
This should take all of the stock, but you don't want to make this to wet. Your stuffing will be fully hydrated when you can eat a cube or two and its no longer dry in the center, and if you shake your pot it'll kind of jiggle like pudding.
At this point you can add in your chopped sage, check your salt and pepper and remove from heat.
Rub your baking dish with the remaining 2 Tbsp of butter and transfer the stuffing from your pan to the baking dish.
Bake at 350℉ for about 30 minutes. Rotating halfway through.
Your stuffing will be ready when its nice and golden brown on top.