Preheat your oven to 275°F (135°C).

Remove the membrane from the back of the pork ribs.

In a medium bowl, combine brown sugar, smoked paprika, garlic powder, onion powder, chili powder, black pepper, salt, and optional cayenne pepper. Stir until blended.

Rub a thin layer of olive oil over each rack of ribs and generously sprinkle the spice mixture across the meat side, massaging it in.

Wrap each rack of ribs in aluminum foil with the meat side facing up.

Bake the wrapped ribs in the preheated oven for 2.5 to 3 hours.

Unwrap the foil and brush a generous layer of barbecue sauce over the ribs.

Preheat your grill or broiler to high heat and cook glazed ribs for about 5-7 minutes per side.

Let the ribs rest for about 10 minutes, then serve with sides like coleslaw or cornbread.