Ingredients: 3/4 cup butter or margarine, 3/4 cup flour, salt, 1/8 teaspoon nutmeg, 1 quart milk, 2 cups undiluted chicken broth, 4 egg yolks, 1 cup heavy cream, 1/2 cup sherry, 1 pound thin spaghetti, 6 cups leftover turkey cut into cubes, 1 cup fresh or canned sliced mushrooms, 8 oz sharp Cheddar grated (2 cups).
Sauce: Melt butter in large pan, remove from heat. Stir in flour, nutmeg and salt until smooth. Gradually add milk and broth, stirring constantly. Boil 2 minutes until slightly thick.
In small bowl, beat egg yolks and cream. Beat in a little of the sauce, pour back into pan over low heat, stirring until hot but not to a boil. Stir in sherry.
Boil spaghetti, drain and return to kettle. Add 2 cups sauce and toss together. Divide in half and put into two 12-by-8-by-2 baking dishes, push back toward edges. Add 2 cups sauce to turkey and mushrooms, mix well and spoon half into center of each dish.
Sprinkle grated cheese, cover with foil and refrigerate 1 hour or even overnight. Preheat oven to 350F and bake, covered, 45 minutes. Spoon reheated leftover sauce over each serving. You can refreeze and have leftover leftovers.
Somewhat calorific, but then again, so are the bread and mayonnaise for turkey sandwiches, which won't taste nearly this good.