Separate lumps of crab meat and remove any bone or shell. Place in shallow baking dish. Melt butter; add flour, making a smooth paste. Stir in evaporated milk and bring to a slow boil. Simmer 2 minutes. Add well-beaten egg yolks, salt, cayenne, horseradish and sherry. Cover and cook over low heat for 3 minutes longer. Pour over crab meat. Sprinkle with paprika. Bake at 350 degrees for about 10 minutes.