Place the tomato sauce, tomato paste, apple cider vinegar, molasses, mustard powder, garlic powder, onion powder, sugar, cumin, cayenne pepper, salt, and pepper in a medium bowl. Whisk together to combine.
Place the chicken breasts in the bottom of the crock pot. Pour the BBQ sauce over the chicken. Place lid on crock pot.
Cook on high for 2-3 hours or on low for 6-7 hours.
Once the chicken is cooked, use two forks to shred the chicken.