In a 3 1/2, 4, 5, or 6-quart crockery cooker combine white wine, onion, garlic, and bay leaf. If turkey roast is wrapped in netting, remove netting and discard. If gravy packet is present, remove packet from roast; refrigerate packet for another use. Combine rosemary and pepper. Rub roast with rosemary mixture. Place turkey roast in cooker.
Cover; cook on low-heat setting for 10 to 12 hours or on highheat setting for 4-1/2 to 5-1/2 hours. Remove roast and keep warm. For gravy, strain cooking juices; discard solids. Skim fat from juices. Measure 1-1/3 cups juices into a small saucepan. Combine cream or milk, cornstarch, and salt; stir into juices. Cook and stir till thickened and bubbly. Cook and stir 2 minutes more.
Slice turkey roast. Spoon some gravy over roast. Pass remaining gravy with roast.