The large ham that is indispensable on the Australian Christmas table, Ommis is slowly roasted over high fire, and is brushed with spiced cream maple syrup layer by layer, leaving you with a delicious aroma! How to eat: (This is heated and ready to eat) Thaw the Christmas ham in advance. Brush the surface of the ham with mustard maple syrup, preheat the oven to 170 degrees, and bake the ham for 35-40 minutes, until the skin turns golden brown.