Remove membrane from back of ribs and pat dry.
Preheat oven to 325ºF (160ºC). Sprinkle salt, pepper and garlic powder all over ribs. Lightly spray or oil a large piece of foil. Wrap rack with foil and place on baking sheet. Roast for 1 1/2 hours. Remove foil from ribs. Carefully wipe baking sheet with paper towel and line with parchment paper.
Cut ribs into single ribs. Whisk cranberry sauce and chili sauce in a large bowl. Add ribs and toss well to coat with sauce. Place ribs on prepared baking sheet and return to oven for about 30 minutes, until ribs are well glazed and sauce thickens.