Preheat oven to 375ºF. Spray large baking dish with cooking spray.
Place hot dog buns into a baking dish.
Inside of each bun add condiments of your choice, such as mustard, ketchup and relish.
Place the hot dogs into each bun.
Top each hot dog with ¼ cup of chili.
Sprinkle the shredded cheddar cheese across the top of the chili dogs, followed by the diced onions.
Cover the baking dish with foil and bake for 25-30 minutes, or until the cheese is melted and chili dogs are warmed through.
Allow to cool for 5 minutes before serving, enjoy!