It’s a copy of a "Pitchfork" hot dog at a local place I mentioned in another thread. Here’s a photo of the restaurant version:
They use real shredded cheddar, diced onions cooked on a flat-top grill in a little oil, and bacon cooked on the same grill.
I nuked the bacon, and used some Velveeta that was in the fridge (we use it to make Rotel & Velveeta dip) that I melted in the microwave. I also thought of using strips of american cheese, and then sticking it under the toaster oven broiler to melt it. The restaurant version used something that tasted like KC Masterpiece; I use whatever is on hand in the house.
The flavor combination works well, in my opinion. Of course, the better each of the ingredients is, the better will be the end result.