Mix the garlic, ginger, orange marmalade and soy sauce together in a large bowl.
Add the chicken thighs, stir, cover and set aside for 15min.
Put the chicken in a roasting tin and roast at 425°F for 35min, basting and moving the chicken around in the tin so that it cooks evenly and is cooked to the centre. Lift the chicken out of the tin and keep warm.
Skim the fat off the juices in the roasting tin, discard the fat, bring the juices to the boil and bubble for 30sec. Spoon the juices over the chicken, sprinkle the sesame seeds over and serve with boiled white rice.