A classic use of leftovers, personally made with your favorite toppings.
Preheat oven to 400
While your oven is preheating cook your hot dogs however you like boil, grill, microwave...doesn't matter. Since it's winter I boiled mine until heated through- about 10 min.
Spread tops of the buns with butter, and toast the buns in the oven until the butter melts and your exterior is firm; about 4 minutes. Since the buns are closed the inside will still be soft, but the outside will be able to hold up to the chili without falling apart.
Microwave enough of your leftover chili for however many dogs you are cooking until it's hot. Set aside.
Right when you take the buns out of the oven place two slices of American cheese in the slice, followed by the hot dogs, then using a slotted spoon add the chili.
Now have fun and top however you like or with whatever you have on hand. I went classic with shredded cheddar cheese and sour cream. My husband chose hot giardiniera. See above for other ideas.