Preheat oven to 400° F.
Scrub the skins of the potatoes and pat dry with a kitchen towel or paper towel. Pierce each sweet potato in multiple places with a fork. Individually wrap each one in aluminum foil.
Place the wrapped sweet potatoes on a baking sheet lined with foil. Bake for 45-60 minutes (or longer if necessary) until tender. Allow the potatoes to cool for about 5 minutes before handling them.
Reheat leftover chili in a saucepan on the stovetop or in a microwave-safe container in the microwave or until thoroughly heated. If you're using canned chili, follow the heating instructions on the label.
Use a knife to make a slit lengthwise through the top of each sweet potato about 1/3 to 1/2 of the way down. Fill the inside of each sweet potato with 3/4-1 cup of chili. Add desired toppings.