Slice off the top and bottom of the orange, then peel all round the fruit down to the flesh. Using a sharp knife, cut out the segments between the white membranes and retain the juice (approx. 250 ml), set aside. Spoon the jam into a pan along with the orange segments and retained juice, bring to the boil over a medium heat, stirring occasionally, then simmer for approx. 2 mins.
Place the cheese slices in the raclette pans, top with the orange and rosemary. Melt under a raclette grill for approx. 8 mins.