1. Preheat oven to 300 degrees F.
2. Combine brown sugar, paprika, chili powder, salt, black pepper, garlic powder, celery seeds, and cayenne in a medium bowl. Mix together with a fork, mashing any lumps of brown sugar.
3. Place rib racks on a large broiler pan or rimmed baking sheet. Generously rub spice mixture all over both sides of ribs, leaving racks bottom (bony) side up. Bake for 45 minutes. Turn racks over and cook for another hour or more, until a fork easily pierces the meat. (Ribs can be cooked up to two days ahead. Cool, wrap in foil, and refrigerate.)
4. Heat grill to medium. Have ribs at room temperature. Grill rib racks for 5 to 10 minutes per side or until lightly charred and heated through. Transfer to a cutting board and cut in between the bones to separate into individual ribs. Place ribs on a platter. If desired, serve with Kansas City-Style Barbecue Sauce.
Source: Hannaford fresh Magazine, July - August 2008