Place the chicken breasts in the crockpot.
In a bowl, mix teriyaki sauce, garlic, ginger, honey, and sesame oil.
Pour the sauce mixture over the chicken in the crockpot.
Cover and cook on low for 4-6 hours or high for 2-3 hours.
If using, add broccoli florets in the last 30 minutes of cooking.
Once cooked, remove the chicken and shred it using two forks.
Mix cornstarch with a little water to create a slurry.
Add the slurry to the sauce in the crockpot and stir until thickened.
Return the shredded chicken to the crockpot and mix well.
Serve over cooked rice, garnished with sesame seeds and green onions.