Spray slow cooker with cooking spray.
Season both sides of chicken with lightly with salt and pepper, and place in the bottom of slow cooker.
In a small bowl, add honey, soy sauce, onion, ketchup, oil, garlic and pepper flakes and stir until well combined. Pour over chicken.
Cook on low for 3-4 hours, or just until chicken is cooked through.
Remove chicken from slow cooker, leave sauce. Dissolve 4 teaspoons of cornstarch in 6 tablespoons of water and pour into crock pot. Stir to combine with sauce.
Replace lid and cook sauce on high for ten more minutes or until slightly thickened.
Cut chicken into bite size pieces, then return to pot and toss with sauce before serving.
Sprinkle with sesame seeds and serve over rice or noodles.