To ensure that the lasagna doesn't come out watery, it's important that the greens go in dry. Let all the water evaporate during cooking, and then blot the leaves with a paper towel if necessary after removing them from the saute pan.
The crepes can be refrigerated, wrapped in plastic wrap, up to two days; or frozen, wrapped in paper towels (to absorb moisture when thawing) and plastic wrap, and placed in a freezer bag, up to one month. Thaw completely before filling. The mushroom filling can be made two days ahead and stored in the refrigerator. When Martha made these crepes on Cooking School episode 404, she made a half recipe and finished each serving with a fried egg.