Simmer chicken in barely enough salted water to cover, a slice or two of onion, and a bay leaf. When tender, remove meat and cut in dice, not too small. Melt 1/4 butter in skillet and sauté mushrooms 2-3 minutes. Add chicken meat, cream, wine, season to taste, and heat almost to boiling. Knead flour and 2 tablespoons butter to a smooth paste and stir into the chicken mixture, continuing to stir until smooth and somewhat thickened. Let simmer about 5 minutes.
In the meantime, cook spaghetti or noodles in salted water until just tender, 7-10 minutes. Drain, rinse in cold water, and spread on bottom of shallow greased casserole dish. Pour the chicken-mushroom mixture gently over it, sprinkle with grated Parmesan cheese, and bake at 375° for about 20 minutes or until top is golden brown. If you are making it at serving time, so that all ingredients are hot, merely slide it under the broiler and brown. Serves 4.