01 -
Preheat oven to 163°C. Line a large roasting pan with aluminium foil and set a roasting rack on top. Tuck orange slices, garlic slices, and rosemary sprigs between the ham slices. Position the ham cut side down on the rack.
02 -
Cover ham loosely with foil and bake in the oven for 1 hour and 45 minutes.
03 -
In the final 15 minutes of initial baking, combine orange marmalade, brown sugar, honey, Dijon mustard, orange zest, and orange juice in a small saucepan. Whisk over medium-low heat until smooth and the sugar has dissolved.
04 -
Remove ham from oven and discard the foil. Generously brush the entire surface of the ham with the prepared glaze.
05 -
Return ham to the oven, uncovered, and bake for an additional 45 minutes, brushing with more glaze halfway through, until caramelised and glossy.
06 -
Remove ham from oven and tent loosely with foil. Allow to rest for at least 15 minutes, then transfer to a serving platter. Slice around the bone and serve warm.