3 Tbsp dark brown sugar
2 tsp Chili Powder
2 tsp Paprika
1-1/2 tsp Ground Black Pepper
1 tsp Dry Mustard
1 tsp Onion Powder
1 tsp Salt
1/4 tsp Cayenne Pepper
3 lbs bone-in, skin-on chicken pieces (breasts halved crosswise, leg quarters separated into thighs and drumsticks)
Rub Chicken– Combine the dry ingredients – brown sugar, chili powder, paprika, pepper, dry mustard, onion powder, salt, and cayenne – in a bowl. Mix with a fork to blend. Transfer half of dry rub to shallow dish; reserve for later use. Rinse chicken pieces briefly in cool water; dry with paper towels. With remaining rub, coat the chicken pieces over and under skin. Transfer chicken pieces to plate and refrigerate, covered, 30 min (or up to 1 hour).
Grill Chicken – Prepare grill for cooking on high heat, with all burners on high, grill covered, for 15 min. Once grill is blisteringly hot, turn all burners to medium-low. Scrape and oil the heated cooking grate. Arrange chicken, skin side down, on the grate and grill until skin is well browned and crisp, 15 to 20 min. Remove from grill momentarily.
Dredge – Lightly coat skin side of chicken with reserved spice rub and return pieces to the grill, skin side up. Continue to grill the chicken pieces, covered, until rub coating has melted into a glaze and white meat registers 160 degrees (and dark meat 175 degrees), about another 15 to 20 min. Transfer grilled chicken to a large serving platter. “Tent” the platter with foil, and let rest 5 min while juices redistribute in the meat. Serve.