Add the onion, orange juice, ketchup, orange marmalade, apple cider vinegar, soy sauce, Dijon, five-spice, paprika, black pepper and garlic to a large resealable plastic bag. Close the bag and shake to incorporate. Add the chicken drumsticks to the bag. Reseal and marinate for at least 1 hour in the refrigerator. (Chicken can be prepped the day before and refrigerated overnight.)
Preheat oven to 400 degrees F.
Pour the entire contents of the bag onto a foil-lined sheet tray. Bake, turning the drumsticks halfway through baking, until the chicken is cooked through, the juices run clear and an instant-read thermometer inserted into the thickest part of meat (avoiding bone) registers 160 degrees F, about 25 minutes.
Remove to a platter and let rest 5 minutes, then sprinkle with parsley and serve warm.