Combine all spices in a small bowl. Reserve 1 tsp of mix for BBQ sauce.
Place chicken in slow cooker. Sprinkle the spice mix over the chicken.
Cover and cook on high for 3-4 hours. Once done cooking, use two forks, a hand mixer or stand mixer to shred the meat. Set aside and keep warm.
For the Cranberry BBQ sauce
Saute the onion in about 1 Tbsp olive oil until softened, about 3-4 minutes. Add whole cranberry sauce, apple cider vinegar, Worcestershire sauce, mustard, ketchup and 1 tsp reserved spice mix. Cook for about 5 minutes till thickened and bubbling.
Remove chicken from slow cooker and top with BBQ sauce.