Melt the butter. Trim the cut ends of the asparagus and wrap each spear in a slice of Prosciutto ham. Lay them on a baking tray, brushing them lightly with the melted butter to ensure they do not stick.
Cook in a preheated moderate oven (Mk 4 - 350ºF - 180ºC) for 10-15 minutes (depending on the thickness of the asparagus) until the asparagus is nicely roasted and the ham is crispy. Serve hot.