Place the chicken breasts in the bottom of your slow cooker, sprinkle with a little salt and pepper.
In a separate bowl, whisk together the honey, soy sauce, blackberry jam, hoisin sauce, garlic, onion, olive oil and red pepper flakes. Pour sauce over chicken breasts.
Cover and cook on LOW for 4-5 hours until the chicken is cooked through.
Remove chicken from slow cooker, keeping liquids in the slow cooker, and place chicken in a bowl. Remove the bones and shred chicken. Leave shredded chicken in the bowl.
In a small bowl, whisk together the cornstarch with 3 Tbsp of cold water. This is called a slurry, and it will thicken the sauce.
Transfer the liquids from the slow cooker to a small saucepan over medium high heat and whisk in the slurry. Bring sauce to a boil and cook until it reduces and thickens slightly. This took me about 3-4 minutes.
Pour half the sauce over shredded chicken and toss to combine. Top chicken with scallions and sesame seeds.
Pour the second half of the sauce into a small bowl or gravy boat to pour over chicken later if desired.