Step 1

Stir 2 tablespoons packed brown sugar, 1 1/2 teaspoons paprika, 1 teaspoon ground cumin, 1 teaspoon garlic powder, 1 teaspoon onion powder, 1 teaspoon dried ground mustard, 1 teaspoon kosher salt, 1/2 teaspoon chili powder, and 1/4 teaspoon black pepper together in a large bowl.

Step 2

Pat 2 1/2 pounds bone-in, skin-on chicken pieces dry with paper towels. Use your fingers to gently loosen and pull the skin away from the meat without removing it. Place in the bowl and rub all over with the spice mixture, working it gently under the skin. If grilling immediately, let sit at room temperature for at least 20 minutes while you heat the grill. Otherwise, cover and refrigerate up to overnight.

Step 3

Heat a gas grill for direct, medium heat (about 350ºF), or prepare a charcoal grill for both direct and indirect medium heat (pile the coals on one half the grill). If the chicken has been refrigerated, let it sit at room temperature while the grill is heating. Measure out 1/2 cup barbecue sauce.

Step 4

Scrape the grill grates clean if needed. Oil the grill grates with a folded paper towel dipped in vegetable oil. Place the chicken on the grill skin-side down in a single layer, grilling over direct heat if grilling on charcoal. Cover and cook undisturbed until grill marks form on the bottom and the skin is lightly crisped, 3 to 4 minutes. If the chicken sticks to the grill, continue to cook for another minute until it releases easily. Flip, cover, and cook until grill marks appear on the second side, 1 to 2 minutes more.

Step 5

Reduce the heat to low on a gas grill, or move the chicken (but do not flip) over indirect heat on a charcoal grill. Brush the chicken with some of the barbecue sauce. Cover and grill for 5 minutes. Flip and brush the chicken with sauce every 5 minutes until cooked through and an instant-read thermometer in the thickest part of the meat not touching bone registers at least 165ºF, about 10 minutes more. Serve with more barbecue sauce if desired.