Marinate chicken legs in teriyaki sauce for a minimum of 1 hour, turning occasionally.
After chicken has marinated, discard excess marinade. Preheat oven to 375°F.
Place sliced shallots evenly on a baking sheet. Remove chicken from marinade and place on top of shallots, season with ground black pepper.
Take the butter and spread it under the skin of the chicken evenly.
Cook chicken for 25 minutes. Add grape clusters and continue to cook until chicken reaches an internal temperature of 165°F, approximately 20-25 more minutes. Allow chicken to rest for five minutes before serving.
Notes
Excellent paired with sautéed spinach or a green salad.