Preheat oven to 450° fahrenheit. In a medium bowl, stir together garlic, ginger, marmalade, lime juice, orange juice, soy sauce, honey, coriander, five spice, siracha, and pepper.
Place drumsticks into a ziploc bag. Add marinade. Seal and refridgerate for anywhere from 1 hour to overnight.
Remove marinated chicken from bag, reserving marinade for later.
Place chicken on a baking rack over a foil-lined baking sheet.
Using a sharp knife, score chicken in a criss-cross pattern. The goal is to slice through the skin and some of the meat.
Bake for 35 minutes or until juices run clear and chicken is cooked through.
While chicken is cooking: Place reserved marinade in a pan on the stove. Bring to a boil, and simmer rapidly until marinade has reduced by half and has become a sticky, sweet sauce (it should coat the back of a spoon).
Remove cooked chicken from oven. Brush with thickened sauce, making sure to cover all sides of the drumsticks.
Bake drumsticks for 5 more minutes, or until sauce has caramelized and is thick and glossy on the chicken.
Place chicken on a platter, and top with garnishes, if desired.