Unfortunately, I couldn't find my old recipe, so went online and found this one, which is nearly the same as mine...tetrazzini is a classic dish and hasn't changed that much over the years. But if I recall correctly, I put fresh nutmeg in mine plus my sauce was much thicker than this one turned out to be, so I'd use more than 1/4 cup flour if I made this recipe again. I made the corrections in the recipe below.
Still, it brought back some fun memories. And I still have Lynn's Beef Stroganoff recipe!
10 ounces mushrooms, sliced thin (about 4 cups)
5 tablespoons unsalted butter
1/4 to 1/3 cups all-purpose flour (I found 1/4 did not make the sauce as thick as I'd like.)
1 3/4 cups milk
some grating of fresh nutmeg
2 cups chicken broth
1/4 cup dry white wine
10 ounces spaghetti
3 cups coarsely chopped cooked turkey, including cooked giblets if desired
1 cup cooked peas
2/3 cup freshly grated Parmesan
1/3 cup fine fresh bread crumbs
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. The Tetrazzini may be prepared up to this point 1 month in advance and kept frozen, covered. Bake the Tetrazzini in the middle of a preheated 375°F. oven for 30 to 40 minutes, or until it is bubbling and the top is golden.