MAKES 6 SERVINGS

Certain vegetables don’t require a tomato sauce to show off in lasagna, while some (beets) would even clash with tomato sauce. In the spring, when asparagus, artichokes, and fava beans are so sweet and delicate, I want to embellish them only with a béchamel enhanced with fresh herbs and Parmesan cheese. These are less rustic, more elegant, than the tomato-based lasagnas, and the béchamel takes no more time to make than a marinara (less, in fact). But it can’t be made too far ahead, so these can’t be made on a whim the way the tomato lasagnas can when you have marinara sauce stashed in the freezer.

2 tablespoons extra virgin olive oil (or 1 tablespoon olive oil and 1 tablespoon unsalted butter); plus 1 tablespoon olive oil, for drizzling (optional)
2 tablespoons minced shallot or onion
2 tablespoons sifted all-purpose flour
3 cups milk (1 percent, 2 percent, or whole)
Pinch (very small) of freshly grated nutmeg
Salt and freshly ground pepper
4 ounces Parmesan, grated (1 cup)
¼ cup finely chopped fresh herbs, such as parsley, tarragon, chives
½ pound (more or less) no-boil lasagna noodles (depends on the size and shape of your baking dish)

Vegetable preparation of your choice (see variation recipes)

  1. To make the béchamel, heat the oil (or oil and butter) over medium heat in a heavy medium saucepan. Add the shallot or onion and cook, stirring, until softened, about 3 minutes. Stir in the flour and cook, stirring, until smooth and bubbling, but not browned, about 3 minutes. It should have the texture of wet sand at low tide. Whisk in the milk all at once and bring to a simmer. Whisking all the while, simmer until the mixture begins to thicken. Turn the heat to very low and simmer, stirring often with a whisk and scraping the bottom and edges of the pan with a heat-proof spatula, until the sauce is thick and has lost its raw flour taste, 10 to 15 minutes. Season with the nutmeg and salt and pepper to taste. Strain while hot into a large measuring cup or a medium bowl. Stir in ¼ cup of the Parmesan and the fresh herbs.
  2. Heat the oven to 350°F. Oil or butter a rectangular baking dish. It should have a capacity of at least 2 quarts. Spread a thin layer (about 1⁄3 cup) of béchamel over the bottom. Top with a layer of lasagna noodles. Spoon about 1⁄3 cup béchamel over the noodles. Top with half of the vegetables and sprinkle with about 1⁄3 cup of the Parmesan. Repeat the layers, then end with a layer of lasagna noodles topped with béchamel and Parmesan. Make sure the noodles are well coated with béchamel so they will be sure to soften during baking. If desired, drizzle 1 tablespoon olive oil over the top.
  3. Cover the baking dish tightly with foil (it’s important to crimp the foil tightly against the edges of the pan so that the dish is sealed and the lasagna noodles steam and don’t dry out). Bake until the noodles are tender and the mixture is bubbling, 30 to 40 minutes. Uncover and, if you wish, bake until the top begins to brown, another 5 to 10 minutes, but make sure that the noodles are completely covered with béchamel. Remove from the heat and allow to sit for 5 minutes before serving.

ADVANCE PREPARATION: You can assemble this up to a day ahead and refrigerate, or freeze for a month. The lasagna can be baked several hours ahead and reheated in a medium oven.

Béchamel

Béchamel is the classic white sauce that is one of the “mother sauces” in traditional French cooking. It also exists in Italian cuisine (besciamella). It is made by whisking milk into a paste of flour and butter called a roux. When the mixture reaches the boiling point it thickens into a smooth sauce, which is simmered until there is no longer any trace of a raw flour taste. Although this white sauce is often referred to as a cream sauce, there is rarely any cream in it. What causes it to be creamy and rich is the suspension of the roux in liquid.
Though the classic French béchamel and Italian besciamella are made with butter, Provençal cooks often use olive oil, and olive oil béchamel is delicious. That’s the sauce I use for my vegetarian lasagnas (though I give you the choice of using a combination of the two). The lasagnas don’t include lots of heavy cheese, just vegetables, pasta, béchamel, and Parmesan.
If you’re new to cooking you may have steered away from French sauces, but they are not difficult at all to make. The first step is making the roux—the flour and olive oil (or butter) paste. You simply combine the two ingredients and stir over medium heat for 3 to 5 minutes, until the mixture has a texture resembling wet sand at low tide and no longer has a raw floury taste. Then you whisk in the milk and whisk until the sauce thickens. It will do so as soon as it reaches a simmer. Then it’s just a question of simmering the sauce for 10 to 15 minutes, until the sauce is velvety and has no floury taste. In cooking school, they tell you that you must simmer the sauce for at least 20 minutes in order for the roux to be properly dispersed in the liquid and reach its maximum viscosity. But I’ve found 10 to 15 minutes to be sufficient for this amount of béchamel.