Preheat the oven to 400 F (204 C). Pat the 6 chicken thighs dry with paper towels. Season both sides with the 1 teaspoon salt, ½ teaspoon black pepper, and 1 teaspoon garlic powder.
Heat the 1 tablespoon olive oil in a large oven-safe skillet over medium heat. Place the chicken thighs skin side down and cook undisturbed for 6 to 8 minutes, or until the skin is deeply golden and releases easily from the pan. If the chicken sticks, let it cook another minute before trying again. Flip and cook for 2 to 3 minutes more.
Carefully pour off all but about 1 tablespoon of the rendered fat. Transfer the skillet to the oven. If your skillet isn't oven-safe, transfer the chicken to a baking dish, skin side up.
Bake until the thickest part of the chicken reaches 175 F (79 C), about 20 to 25 minutes.
While the chicken bakes, combine the ½ cup honey, 6 cloves minced garlic, 3 tablespoons low sodium soy sauce, 1 ½ tablespoons apple cider vinegar, and ¾ teaspoon crushed red pepper flakes in a small saucepan over medium heat. Bring to a gentle simmer, stirring occasionally.
In a small bowl, whisk together the 1½ tablespoons water and 1½ teaspoons cornstarch until smooth. Stir the slurry into the sauce. Simmer, stirring constantly, until the sauce thickens enough to coat the back of a spoon, about 2 to 3 minutes.
Remove the chicken from the oven. Spoon or brush enough glaze over the tops of the chicken thighs to coat them evenly, reserving the remaining glaze for serving. Return the chicken to the oven and broil for 3 to 5 minutes, watching carefully, until the glaze is bubbling and lightly caramelized.
Let the chicken rest for 5 minutes. Spoon the reserved glaze over the chicken and garnish with sesame seeds and sliced green onions before serving.