Cut turkey into small pieces. Heat 1 tablespoon butter in a nonstick pan over medium heat. Add turkey; cook 2 to 3 minutes or until golden and cooked through. Season with salt and pepper; transfer to a plate.
Wipe mushrooms with paper towel. Discard stalks. Heat remaining 1 tablespoon butter in pan over medium heat. Add mushrooms, open side up, and cook 3 minutes. Add wine, bay leaf, rosemary and a generous grinding of pepper. Cook, covered, another 5 minutes.
Transfer mushrooms to a plate. Cook pan juices over high heat until reduced to one third their original volume. Discard rosemary and bay leaf. Leave pan juices to cool.
Pour pan juices into a large bowl. Whisk in oil, vinegar and crème fraîche. Add salt and pepper to taste. Finely chop 4 lettuce leaves. Add to bowl with turkey; stir to combine.
Spread remaining whole lettuce leaves on serving plates. Place mushrooms on top, open sides up, and fill with turkey salad. Garnish with raspberries.
Raspberries are an excellent source of vitamin C. They are also high in pectin, a form of soluble fibre that helps control blood cholesterol levels. In addition, they provide bioflavonoids that may protect against cancer.