If you want to indulge in a delicious, rich meal, make this lasagna. This is a meal I will only make on occasion since it's full of butter, something I try to use minimally or for baking. It's also a messy meal to make, using 5 big dishes/pots. But once you try your first bite of this, you'll realize it was worth the effort (and calories). This lasagna is the perfect comfort food to make on a cold evening. And trust me, although 3 pound of mushrooms sounds like a lot, you could use even more if you want. They lose lots of volume once you cook them.
When I first made this lasagna I tried to skip a step and use no-boil lasagna noodles. Turns out this was a bad idea. The no boil noodles require more liquid around them in the baking process to soften, which doesn't happen with the béchamel sauce. Put in the extra effort of boiling lasagna noodles and save yourself the let down of slightly crunchy noodles. This lasagna can be made ahead of time and can be frozen if you want. Leftovers on day 2 were just as good as day one.
Adapted from Ina Garten via Smitten Kitchen
Serves 6 to 8
3 to 6 tablespoons olive oil
3/4 pound dried lasagna noodles
1 large clove garlic, minced
4 cups whole milk
1 stick (113 grams) unsalted butter
1/2 cup all-purpose flour
1 teaspoon freshly ground black pepper
3/4 teaspoon ground nutmeg
48 ounces (1.4 kilos or 3 pounds) cremini mushrooms, sliced into 1/4" pieces
1 1/2 cup freshly grated Parmesan
In a large pot of boiling, salted water, cook the noodles for 10 minutes. If you want to cut down on dishes, cook these noodles in a wide pot and use it again for the mushrooms. Drain and set aside.
Preheat your oven to 375ºF/190ºC.
To make the béchamel, bring the milk and garlic to a boil in a saucepan. Once boiling, remove from heat. In a large saucepan, melt the butter. While whisking constantly, add the flour and cook for 1 minute. Keep whisking and slowly add the milk mixture. Pour it a little at a time and make sure it's fully incorporated into the flour mixture before adding more. Once half the milk has been mixed in, you can add the rest in one pour. Add 1 1/2 teaspoons salt, the pepper, and the nutmeg. Over medium-low heat keep whisking or stirring the béchamel for about 5 minutes, until it begins to thicken.
To prepare your mushrooms, heat 1 or 2 tablespoons of olive oil in a large saucepan. Cook your mushrooms in batches (I cooked mine in 3 batches), adding a pinch of salt to each batch. Cook each batch for about 5 minutes, until tender and the mushrooms begin to release their juices. Be sure to stir the mushrooms a couple times during this process. Repeat this with the remaining batches of mushrooms, using more oil if needed. After each batch is done, place it in a colander to drain the excess liquid.
To assemble the lasagna, begin by spreading some of the béchamel sauce on the bottom of a 9x13" baking dish. Add a layer of noodles over the béchamel (I do not make my noodles overlap), then add 1/4 of the remaining sauce, 1/3 of the mushrooms, and 1/4 cup of Parmesan. Repeat this process 2 more times, layering the noodles first, followed by the béchamel, mushrooms, and finally the Parmesan. Top the final layer with one more layer of noodles, the rest of the béchamel, and 3/4 cups Parmesan.
Bake for 40 to 45 minutes, until the top is browned and the sauce bubbles.