7. Lay the terrine in a deep roasting tin and cover with cold water. Heat on the hob to a temperature of 80°C, cover with foil and transfer to the oven. Cook for approximately. 1 hour. Test the internal temperature with a probe at the end of the cooking time; it should be between 70–75°C. If you have a steam oven, the terrine could be steamed as an alternative.
8. Allow the terrine to cool for 20 minutes and then transfer to iced water. Ideally use a roasting tin of iced water that can then be put in the fridge. Allow to chill completely.
9. Lay out sheets of cling film as you did when shaping the terrine. Starting 10cm in from the short edge, lay two of the prosciutto slices lengthwise left to right, overlapping them slightly. Lay the other four slices running away from you, starting at the far edge of the first two slices, to give a rectangle roughly 30cm x 25cm. Unwrap the chilled terrine and put any jelly and juices in a small pan. Reduce this liquid down to a syrup and brush over the ham; this will help to stick the ham to the terrine. Lay the terrine on the ham close to the long edge and, with the help of the cling film, wrap the ham tightly around the terrine. The terrine will end up in the middle of the cling film sheet. Straighten the film out and carefully roll the terrine back to the edge of the film. Wrap as tightly as possible in the film and twist the ends tightly. Tie the ends to keep everything in place and chill the terrine.
10. To serve, slice the terrine, allowing two slices per person. It will be easier to slice through the cling film and remove this afterwards. Allow the terrine time to come to room temperature before serving. Pickled mushrooms, apple chutney, cornichons, sourdough toast, brioche – all would make good partners for the terrine alongside a few simply dressed leaves.