Preheat oven to 180°C, fan-forced. Position an oven shelf in the lowest position and remove all the other shelves.
Use a small sharp knife to cut around the ham shank (end of the leg) in a zigzag pattern 10cm from the end. Carefully remove the skin from the ham in 1 piece by running the knife and score the fat in a diamond pattern. Place the ham in a baking dish lined with several layers of non-stick baking paper.
Combine the marmalade, sugar, mustard, macadamia butter and chilli sauce in a small saucepan and stir over a low heat until the marmalade melts. Brush the ham with half the marmalade glaze to evenly coat. Bake in the oven for 50-60 minutes or until golden brown.
Press the macadamias firmly onto the ham and brush with remaining glaze. Bake for a further 15 minutes or until nuts are lightly toasted. Remove from the oven and set aside for 15 minutes to rest before carving.