Add a third of the tortilla chips to the bottom of a 12-inch Dutch oven. Cover with a third of the black beans and then a third of the cheese. Repeat layering two more times, ending with cheese.
Cook nachos at 350◦ (use 8 coals underneath and 17 coals on top) until cheese is melted and tortilla chips are starting to brown, approximately 20 minutes.
Carefully fill plates with hot nachos and have everyone add their toppings of choice.