The convenience of the crockpot is that as long as you dump stuff on it and take care of it, it will cook it thoroughly without having to pay any attention to it. Bad thing is that if you forget about it, it can get overcooked, so you do have to be at least a bit careful. Otherwise dry chicken can happen.
Michelle from Nom Nom has a recipe for chicken that makes its own gravy. We need to fry some onions and garlic in butter, to let them sweat, and let their flavors come out.
We add tomato paste and we let it cook for a bit. Now, I know we are not supposed to use acidic food in cast iron because of leaching. I decided to take a risk since we had already added a decent amount of butter to the pan when sweating the onions.