This delicious crockpot chicken barbecue is made with cooked and shredded chicken breasts. Feel free to use all or part chicken thighs in the dish. If you use chicken thighs instead of chicken breasts, they may be cooked for a longer period of time. Feel free to use 1 1/2 cups of barbecue sauce along with the hot pepper flakes and garlic powder and skip the rest of the sauce ingredients. Serve these sandwiches for lunch or dinner with coleslaw and dill pickle slices, or make party-sized sliders.