Pan fry spinach in butter until it is cooked, remove and cool.
Lay proscuitto on a large chopping board, so each piece overlaps by fifty percent. Place lamb loin on top. At one end of the lamb, create a strip of the filling – diced sundried tomato, spinach, pinenuts and crumbed feta. Roll it up tightly and secure with meat bands or butchers string. Rest in the fridge for at least an hour.
Remove from the fridge and brown the outside of the meat (which will be the skin of procuitto), in a hot pan, turning regularly.
Bake, uncovered, in a hot oven for 200°C for 30 minutes. Remove from the oven and rest for 15 minutes. Slice into one inch slices.