Preheat your grill for indirect: Place an aluminum foil pan filled with water under the grill grate and toss a chimney of hot coals alongside.
With a butter knife and some paper towels, remove the membrane under each slab of ribs by inserting the knife between the membrane and one of the bones. Pull the membrane with a paper towel to remove it completely.
Mix the brown sugar, paprika, cayenne powder, salt, black pepper, ground ginger, and dried thyme in a small bowl then apply the rub on both sides of the ribs with your hands so it penetrates the meat.
Place the ribs on the grill grate in indirect heat and toss a few applewood chunks onto hot coals. Close the lid and cook for 2 hours at 300°F. Add all the Apple Butter BBQ Sauce ingredients to a saucepan and simmer for 10 minutes.
After 2 hours of cooking, wrap the ribs in aluminum foil with 1 cup of the Apple Butter BBQ Sauce on top of each. Cook for another 1 hour at 300°F. You know the ribs are done when the meat has shrunk about 1 inch from the bones. Once fully cooked, remove from foil and sear over direct heat for 30 seconds per side to caramelize the BBQ sauce.