Season the ribs. Combine the brown sugar, salt, black pepper, onion powder, garlic powder, paprika, Worcestershire sauce, and liquid smoke. Coat the country style ribs evenly with the mixture, cover, and allow them to rest for 30 minutes to 1 hour.
Bake uncovered. Preheat the oven to 275°F. Arrange the seasoned ribs on a wire rack over a sheet pan or directly on a baking sheet. Bake uncovered for 1 hour to allow the seasoning to adhere to the meat.
Prepare the baking dish. Spread ¼ cup of BBQ sauce across the bottom of a baking dish and add 1 tablespoon of butter. Transfer the ribs into the dish, stacking them if necessary. Spread another ¼ cup of BBQ sauce over the ribs and add the remaining tablespoon of butter.
Cover and cook until tender. Cover the baking dish tightly with aluminum foil and return it to the 275°F oven for 1½–2 hours. Begin checking the ribs after 1½ hours. A toothpick should slide into the meat with very little resistance, or a fork should separate the meat easily with a little pressure. If the ribs are still tough, cover them again and continue baking, checking every 30 minutes until tender.
Broil the first side. Transfer the tender ribs to a sheet pan and switch the oven to broil. Brush one side with some of the remaining BBQ sauce and broil for approximately 5 minutes to help the sauce adhere.
Finish the presentation side. Remove the ribs, flip them over, and brush the other side generously with BBQ sauce. Return them to the broiler for up to 10 minutes, until the glaze becomes sticky and develops darker, caramelized spots. Watch closely to prevent the sauce from burning.
Rest and serve. Remove the ribs from the oven and allow them to rest briefly before serving.