First, preheat your oven to 350 degrees F (about 175 degrees C).
Rub a pinch of salt and slight sprinkling of pepper into the chicken pieces and set it aside whilst preparing the marinade
Marinade: use a food processor or pestle and mortar to pound/blitz the peeled garlic and black peppercorns to a rough dry paste. Add in the salt and continue to blitz/pound as paste becomes moist. Add in Grand Marnier, marmalade, sugar, honey, soy, mint sauce and tomato ketchup and mix well.
Pour this marinade over the prepared chicken, rubbing the marinade well into the meat and set aside for at least 2 hours.
Line baking/roasting tin in foil and place chicken together with marinade in tin.
Cover with foil and pierce the cover to allow steam to escape. Bake at 350 degrees F for 40 minutes; remove the foil cover from the chicken, increase the heat of the oven to 400 degrees F and bake a further 10 minutes or till golden brown.
Skim fat off the drippings and serve as an accompanying sauce.
Serve chicken hot, garnished with a fresh sprig of parsley or rosemary.
Garlic cooking tip: about peeling garlic, Julia Child writes, "To separate the cloves from the head, shave the tops off the head, then bang down on the top of the head with your fist and the cloves will spring free. Except in the early summer, when the heads are firm and young, this technique may not do the trick -- even so, it's a good start for the separation." From "In Julia's Kitchen with Master Chefs"