In a large heavy saucepan cook the mushrooms in 1/4 cup of the 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 the milk, the broth, and the wine, stirring, bring the mixture to a boil, stirring, and simmer the sauce for 5 minutes. In
a kettle of boiling salted water cook the spaghetti until it is al dente and drain it well. In a large bowl combine well the 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. In a small bowl combine well the remaining 1/3 cup Parmesan, the bread crumbs, and salt and pepper to taste, sprinkle the mixture evenly over the tetrazzini, and dot the top with the remaining 1 tablespoon butter, cut into bits. Bake the Tetrazzini in the middle of a preheated 375 degree oven for 30 to 40
minutes, or until it is bubbling and the top is golden.