Melt butter in a large skillet over medium heat. Add celery, onion, and mushrooms and cook until soft. Add cream of mushroom soup and heat until mixture starts to barely bubble.

Add cheese, a couple slices at a time and stir until melted. Repeat until you've incorporated all the cheese. Add in cooked and drained broccoli and stir to combine. Serve in a small Crockpot or chafing dish. Serve with tortilla chips.