Preheat the oven to 400 degrees and grease a 101/2 x 151/2-inch casserole dish. Or make two lasagnas with two greased square pans. Bake one and freeze the other.
pasta, have it ready to cook as soon as the béchamel sauce is done.)
Meanwhile, make the béchamel sauce: Melt the butter in a large saucepan over medium heat. Stir in the flour and cook, stirring, about 3 minutes. Add the milk a little at a time, stirring constantly with a whisk to avoid lumping. When all the milk is mixed in, add the nutmeg and salt.
Continue cooking, stirring constantly, until the sauce thickens and becomes smooth. Remove from the heat and let stand while the pasta cooks.
Drain the pasta and lay it out on a cookie sheet to prevent it from sticking together as it cools.
To assemble the lasagna, spread a thin layer of bolognese sauce (just a few tablespoons) in the prepared casserole, then one-third of the pasta, 2 cups of the bolognese sauce, 2 cups of the bechamel sauce, and 1/2 cup of the Parmesan. Repeat layering two more times. (Refrigerate or freeze any leftover bolognese sauce to serve over pasta for another meal.) Dot the top with the butter to keep the lasagna moist during baking. Bake 20 to 30 minutes until golden brown and bubbly.
Serve with: tossed green salad and Italian Bread, homemade (p. 224) or from the bakery.
Note: Substitute your own fresh pasta (p. 76) for the packaged lasagna noodles.