Peel turnips; cut slice from bottoms to create flat surface. Using melon baller, hollow out turnips, leaving scant 1/2-inch/1 cm thickness all around, reserving flesh. Chop flesh and set aside. In pot of boiling salted water, boil turnip shells until almost tender, about 7 minutes; drain, chill under cold water and drain again.

In nonstick skillet, melt 2 tbsp/30 mL of the butter over medium heat; fry onion, chopped turnip and half of the salt until turnip is golden and softened, about 15 minutes (if not completely soft, add 1/4 cup/60 mL water and continue cooking until softened and water is evaporated). Transfer to bowl and mash well or force through sieve or ricer. Cut prosciutto into fine dice; stir into turnip mixture along with parsley.

Sprinkle insides of turnip shells with remaining salt and pepper. Fill with turnip mixture; place in baking dish just large enough to fit turnips snugly. Melt remaining butter and mix with bread crumbs; sprinkle over turnips. Pour 1/4 cup/60 mL water around turnips. Bake in 400F/200C oven until turnip shells are tender (test with skewer) and bread crumbs are nicely browned, 25 to 35 minutes.

Makes 6 servings.