Preheat oven to 400 degrees F (205 degrees C). Line a baking sheet with parchment paper or aluminum foil that has been sprayed with cooking spray on both sides.

Pat chicken thighs dry with a paper towel and set onto the prepared baking sheet. Using a silicone brush, brush sesame oil onto both sides of the thighs, then season all over with salt and pepper. Roast in oven for 25 minutes.

While chicken is roasting, make teriyaki glaze: Combine 1 cup water, soy sauce, brown sugar, honey, ground ginger, and garlic powder in a medium-sized saucepan, and whisk together over medium heat. Heat the mixture until it begins to steam. In a separate bowl, make a slurry by whisking cornstarch and 1/4 cup water until the cornstarch is dissolved. Whisk the slurry into the saucepan with the soy sauce mixture, and let thicken for 3-5 minutes before removing from the heat. Pour equal amounts of the sauce into two heat-safe bowls (one large, one small) and set aside. (The small bowl will be for the chicken to ensure there isn’t any cross-contamination, and the large bowl will be used to toss the broccoli.)

After the chicken has cooked for 25 minutes, use a clean silicone brush to glaze the chicken generously with the teriyaki sauce from the small bowl. Let roast for another 25 minutes, then glaze chicken thighs again with teriyaki sauce from the same bowl as before.

Add broccoli to the large bowl with the teriyaki sauce, toss to coat the broccoli in the sauce, then add broccoli to the sheet pan in a single layer around the chicken. Cook for another 20 minutes, then remove from the oven.

Garnish chicken and broccoli with sliced green onions and sesame seeds, and serve with rice. Leftovers will keep in a large lidded container for up to 4 days.