Season lamb with salt and pepper. Wrap each cutlet with a piece of prosciutto and secure with a toothpick through the side.
To make pea puree; melt butter in a saucepan over a medium heat. Add garlic and shallots and stir for 1 min. Add peas and stock and cover. Steam for 5 mins. Remove from the heat and season. Using a stick blender or food processor, pulse mixture until most peas are pureed to a dip consistency but some remain whole. Cover to keep warm.
Pour oil into a large non-stick frying pan and heat on medium-high. Add cutlets and cook for 4-5 minutes each side for medium done. Remove toothpicks. Serve on a platter with pea puree.