Preheat your oven to 300 degrees Fahrenheit.
Mix the brown sugar, smoked paprika, cayenne pepper, salt, black pepper, onion powder, garlic powder, and ground mustard in a small bowl. Drizzle the liquid smoke over the ribs and rub it in with your hands, making sure to coat the entire surface of the meat.
Rub the spice mixture all over the ribs, making sure they are evenly coated.
Place the ribs on a baking sheet lined with foil or parchment paper.
Cover the ribs with another piece of foil, crimping the edges to create a tight seal.
Bake the ribs in the preheated oven for 2 hours.
After 2 hours, remove the foil covering and brush the ribs with barbecue sauce.
Lower the oven temperature to 275 degrees Fahrenheit.
Return the ribs to the oven and continue baking for an additional 30 minutes to 1 hour.
Remove the ribs from the oven and let them rest for 5-10 minutes before serving.