Add the apples and onions to the bottom of a large slow cooker.
Combine the garlic powder, chipotle powder, black pepper and kosher salt in a small bowl.
Rub this mixture on the brisket, then place in the slow cooker on top of the apples and onions.
In a medium bowl, combine the ketchup, chipotle pepper, adobo sauce, brown sugar, apple juice, rice vinegar, apple cider vinegar, worcestershire sauce and soy sauce.
Pour this mixture over the brisket.
Slow cook on high for 6 hours or on low for 10-12 hours.
Shred the brisket and lightly toast the buns before serving.
Place the brisket on the buns and top with the slaw.
Notes
Nutritional information provided does not include the optional kale apple slaw topping.