Field Mushroom Saltimbocca

In this recipe for Field Mushroom Saltimbocca from Claire Thomson s Mushroom: 80 Recipes Celebrating Remarkable Mushrooms (Amazon UK Bookshop.org), Thomson replaces the meat protein (usually veal or pork) with large flat mushrooms, retaining the prosciutto (ham) wrapper, sage, butter and wine / marsala. She also adds parmesan cheese to further boost the flavours. This is