What exactly happens when a baked dish of noodles, sauce, and gooey cheese comes out withered and pasty, with tough, brittle pasta edges? The problem lies in the layering method itself: If the filling doesn't cover the noodles, lasagna dries out. With light lasagnas, which often contain less filling, it gets trickier.Solution: Take the time to spread sauce and filling evenly and all the way to the edges, especially on the top and bottom. Putting plenty of sauce (at least ¼ cup) in the pan first will prevent sticking and, if you're using no-boil noodles, help soften the pasta. If you seem to be running low on sauce, stretch it with about ½ cup unsalted chicken stock or wine (red for red sauce, white for béchamel). Spread another ¼ cup sauce on top to keep the lasagna moist when you brown under the broiler later. Be aware that no-boil noodles absorb more sauce, so if you use them, keep the pan covered with foil during baking to retain moisture. Even with conventional noodles, if the assembled lasagna looks like it might get dry as it bakes, minimize evaporation by covering it with foil for about two-thirds of the baking time.