Combine brown sugar, black pepper, onion powder, paprika, and salt in a bowl; rub onto pork chops until coated. Cover chops; refrigerate 6 hours to overnight.

Set an oven rack about 6 inches from the heat source and preheat the oven's broiler.

Place pork chops on a slotted, two-piece broiler pan. Whisk maple syrup and mustard together in a small bowl; set aside.

Broil pork chops in the preheated oven for 5 minutes; flip chops. Broil 5 minutes more. Brush chops with maple syrup glaze; broil 1 minute. Flip chops; brush with glaze. Broil until cooked to your desired degree of doneness, about 1 minute. Transfer chops to serving plates; top with additional glaze, if desired.