Slice the hot dogs into rounds about 1/2 inch thick. Pan-fry the hot dogs in a dry 9-inch ovenproof skillet over medium-high heat until just crispy, 5 to 7 minutes.

Pour the chili over the fried hot dog rounds and mix to combine. Reduce the heat to low and simmer 2 to 3 minutes. Remove from the heat and sprinkle the cheese and the onions, if using, over the top.

Place the skillet in the oven and bake until the chili is bubbling and the cheese is slightly browned, about 12 to 15 minutes.

Refrigerate leftovers for up to 4 days, or freeze for up to a month.