Turn the pot to SAUTE. In the pot, add the 3 tbsp butter and allow it to melt. Then add the ¼ cup carrot, ¼ cup celery, ½ cup onion, and ½ cup apple, and saute until everything is soft.
Add ¼ cup cranberries to the mixture and turn the saute function off.
Add ¾ cup broth, ½ tsp sage, 1 tsp poultry seasoning, ½ tsp celery salt, ¼ tsp black pepper, and 5 oz bread. Mix to combine.
Use cooking spray to coat a glass bowl that will fit inside your pot. Then add the stuffing into the bowl. Cover it with aluminum foil and poke a few holes in the foil.
Add 1 ½ cups of water to the bottom of the pot. Add the trivet into the pot, then place the cake pan on top of the trivet.
Put the lid on the pot and cook for 15 minutes. When the timer is up, perform a Quick Release.
If you want some crispy bits on your stuffing, turn your oven to a HIGH broil and put the cake pan in the oven for a few minutes until the top layer begins to crisp up. Keep a close eye on the stuffing because it can burn easily.