Chop a large peeled turnip into small chunks and cover with water in a saucepan. Boil until chunks are tender. Drain. Hand mash with a little butter and skim milk, salt & pepper to taste. Cool. Add 1 cup plain Stonyfield Farm yogurt, a pinch of cayenne. With a hand mixer, blend until smooth and creamy. Put in a casserole dish and bake at 400 degrees until brown on top.