Place 1 pound chicken drumsticks and 1 full recipe homemade teriyaki sauce in a shallow baking pan or a sealable bag. Turn the chicken to coat evenly, seal or cover, and marinate in the refrigerator for 30 minutes.
Preheat the oven to 425°F (220°C).
Remove the chicken from the marinade, letting excess sauce drip back into the pan or bag. Transfer the used marinade to a small saucepan (do not pour the raw marinade back over the raw chicken).
Arrange the drumsticks in a single layer in a baking dish.
Bring the reserved marinade in the saucepan to a rolling boil and boil for at least 1 minute to make it safe for basting.
Roast the chicken in the preheated oven for 25 to 30 minutes, until cooked through (internal temperature reaches 165°F / 74°C). During the last 5 minutes of cooking, spoon the boiled marinade over the drumsticks to glaze them.
Remove the drumsticks from the oven and let them rest for a few minutes. Garnish with 1/4 cup sliced scallions, if desired, and serve.