10 oz. mushrooms, sliced thin (about 4 cups)
5 tbsp. unsalted butter, divided
1/4 cup all-purpose flour
1 3/4 cups milk
2 cups chicken broth
1/4 cup dry white wine
10 oz. spaghetti
3 cups coarsely chopped cooked turkey
1 cup cooked peas
2/3 cup freshly grated Parmesan cheese
1/3 cup fine fresh bread crumbs

In a large heavy saucepan cook the mushrooms in 4 tablespoons of butter over moderate heat, stirring until most of the liquid they give off has evaporated. Stir in the flour and cook the mixture over low heat, stirring for 3 minutes. Add in a stream (that is pour slowly) of milk, the broth, the wine, stirring bring the mixture to a boil, stirring and simmer the sauce for 5 minutes. In a pot of boiling, salted water cook the spaghetti until it is al dente (cooked) and drain it well.

In a large bowl combine well spaghetti, the mushroom sauce, the turkey, the peas, and salt and pepper to taste. Stir in 1/3 cup of the Parmesan, and transfer the mixture to a buttered shallow 3-quart casserole dish. In a small bowl combine the remaining 1/3 cup of Parmesan, the bread crumbs and salt and pepper to taste. Sprinkle the mixture over the tetrazzini and dot the top with the remaining 1 tablespoon of butter, cut it into bits. Bake in 375°F oven for 30 to 40 minutes.