In a medium size pan or pot, add the cubed cheese, Rotel (do not drain), chili powder, cayenne, and a little salt and pepper.
Melt on low heat, stirring occasionally.
Once melted, add 2-3 tablespoons of water to thin slightly.
Stir in the cilantro. Add more salt and pepper if desired.
Notes
You could also cook this in a crockpot on low heat. You can add 8-10 ounces of ground beef, sausage, or a vegetarian ground meat. Cook the meat before, then stir in once the other ingredients are melted.