Heat the olive oil in a large Dutch oven or deep skillet over medium-high heat.
Add the chicken and cook for 5–6 minutes until lightly browned. Remove and set aside.
In the same pot, sauté the garlic and ginger for about 30 seconds until fragrant.
Stir in the rinsed rice, then pour in the chicken broth.
In a small bowl, whisk together the soy sauce, honey, rice vinegar, sesame oil, cornstarch, water, and optional garlic powder. Pour the sauce into the pot.
Return the chicken to the pot and stir to combine.
Cover and simmer for 18–20 minutes, or until the rice is nearly tender.
Add the broccoli, cover again, and cook for another 5 minutes until the broccoli is crisp-tender and the rice is fully cooked.
Let the casserole rest for 5 minutes, then fluff the rice with a fork.
Garnish with green onions and toasted sesame seeds before serving.