1/2 teaspoon (3 grams) freshly ground black pepper
Heat oven to 350°F (176°C). Line a large rimmed baking sheet with aluminum foil and fit sheet with a roasting rack; set aside.
Remove the silver skin from the underside of the ribs by inserting a paring knife under silver skin and pulling it away from ribs; set aside.
Mix together brown sugar, mustard powder, paprika, cumin, salt, pepper and garlic powder in a small bowl. Rub both sides of ribs with spice mixture. Transfer to prepared sheet. Cover tightly with aluminum foil and bake until ribs are tender, about one hour and 15 minutes.
Heat olive oil in a small saucepan over medium heat. Add onions and cook until soft, about five minutes. Add garlic and cook for an additional one minute. Add bourbon and stir until absorbed, followed by apple butter, ketchup, Dijon, vinegar, Worcestershire sauce, brown sugar, cinnamon, salt and pepper. Bring mixture to a boil and reduce heat to low. Simmer for 35 minutes, stirring occasionally.
Heat broiler to high. Broil ribs in centre of oven until slightly charred, about ten minutes, flipping halfway. Baste and flip repeatedly until caramelized, about 15 minutes. Set ribs aside to rest for five to ten minutes before slicing. Serve with remaining sauce.