In large bowl, whisk together hoisin sauce, soy sauce, sesame oil, chopped ginger, garlic powder and dried pepper flakes. Add the chicken and toss to coat evenly. Set aside to marinate in the fridge for 15 minutes.
Place chicken on a baking sheet lined with foil.
Bake for 45 minutes, turning halfway, continue cooking until cooked through and thickest part of drumstick meat reads 165°F (74°C) on meat thermometer. For crispier chicken, broil for 2-3 minutes at the end, taking care not to burn.
Top with sesame seeds and serve with stir fried vegetables, if desired.