Preheat your oven to 375°F and prepare a 9×13-inch baking pan by lining it with aluminum foil for easy cleanup. Arrange the hot dog buns in the pan, ensuring all eight fit snugly together.

Add desired amounts of ketchup, mustard, and relish to the interior of each bun, spreading evenly along the base. Place one hot dog in each bun over the sauces.

Generously spoon about 1/3 cup of chili onto each hot dog, ensuring even coverage. Sprinkle shredded cheddar cheese over the chili, followed by a scattering of chopped onion.

Cover the baking dish with foil and place it in the oven. Bake for 30 minutes, allowing the cheese to melt and flavors to meld.

Remove from the oven and let the dish rest for 5 minutes before carefully lifting the foil. Use a spatula to serve the chili cheese dogs warm. Enjoy immediately!