Spray a 9x13" baking dish with non stick spray.
In a large mixing bowl, add one can of the chili, the cut hotdogs, and a half cup of cheese. Stir everything together until evenly combined.
Pour this mixture into the prepared baking dish, and spread it out evenly.
Spread the cheese slices evenly out over the top.
Pour the second can of chili evenly out over the top, gently spreading it, but being careful not to disturb the sliced cheese.
Sprinkle half a cup of the shredded cheese evenly out over top of the chili layer.
Open the biscuits and separate them. Cut each raw biscuit into four quarters, and spread the pieces evenly out over the casserole. Sprinkle a half cup of cheese evenly out over the biscuit layer.
Bake the dish at 375° for 25 minutes.
Carefully remove the dish from the oven, cover it with aluminum foil, and bake an additional 10 minutes.
Remove the dish carefully from the oven, take off the foil, and let it rest for five full minutes.
Top the casserole with a drizzle of mustard & ketchup, dill pickle relish, and chopped white onion.
Serve & enjoy!