Preheat oven to 350 degrees F. Prepare 8″ x 8″ baking pan.
Brown turkey and set aside. (Can substitute with 2 cups diced leftover turkey.)
Combine chicken bouillon cubes, water and onion in a saucepan. Bring to a boil. Add turnip, cover and cook 4-5 minutes. Add apples and cook 1-2 minutes longer. Drain and reserve stock. Boil stock, uncovered, to reduce to 1 cup.
In another saucepan, melt butter. Stir in flour; add chicken stock and cream slowly while stirring. Cook over medium heat until thickened. Season with salt, pepper and nutmeg. Remove from heat. Add cooked turnip mixture and turkey. Pour into baking dish.
Mix last 6 ingredients in a bowl to form coarse crumbs. Sprinkle on top of casserole.
Bake for 30-40 minutes or until bubbly and lightly browned.