Preheat the oven to 350 degrees F. Place the ham in a heavy roasting pan.
Mince the garlic in a food processor fitted with the steel blade. Add the marmalade, mustard, brown sugar, orange zest, and orange juice and process until smooth. Pour the glaze over the ham and bake for 1 hour, until the ham is fully heated and the glaze is well browned. Serve hot or at room temperature.