Acorn Squash Lasagna with Béchamel Sauce

Ingredients

• 1 medium acorn squash
• 1 cup whole-milk ricotta cheese
• 4 Tablespoons butter
• 1 medium onion, diced small
• 6 cloves garlic, chopped
• 3 Tablespoons chopped fresh sage
• 1/4 cup all-purpose flour
• 4 cups whole milk
• 1/8 teaspoon grated nutmeg
• 1/2 teaspoon salt
• 1/4 teaspoon freshly ground black pepper
• 1 1/2 cups freshly grated Parmigiano-Reggiano cheese, divided
• 2 eggs
• 15 no-boil lasagna noodles, from one box

Directions

1. Heat the oven to 450 degrees F. Cut the squash in half lengthwise, remove the seeds, and roast it until soft, about 40 minutes. Set it aside until it is cool enough to handle, then scrape the flesh into a medium bowl and mash it with a fork. Mix in the ricotta cheese. Turn the oven down to 375 degrees F.
2. As the squash roasts, warm the butter in a medium pot over medium heat. Stir in the onion, garlic, and sage, and cook, giving it an occasional stir, until the onion starts to soften. Sprinkle in the flour and cook for 1 minute, stirring the whole time and scraping along the bottom of the pot so nothing scorches. Pour in the milk, then add the nutmeg, salt and pepper. Increase the heat to high and bring the sauce to a boil, stirring constantly. Lower the heat so the sauce keeps a lively simmer, and cook, stirring now and then, until it is thick enough to cling to the back of a spoon, about 8 minutes. Take the pot off the heat and stir in 1 cup of the Parmigiano cheese.
3. Lightly beat the eggs in a small bowl. Pour in about 1 cup of the hot sauce very slowly, whisking the eggs with a fork as you go. This gently warms the eggs so they stay smooth in the sauce. Add the egg mixture back to the pot and stir until the sauce is evenly combined.
4. Build the lasagna in a 9x13x2-inch pan. Spoon 1/2 cup of sauce across the bottom. Arrange five lasagna noodles over it, overlapping them a bit and breaking the fifth noodle as needed so the base is covered. Spread half the squash mixture over the noodles, then spoon about 1 1/4 cups sauce on top. Make a second layer with noodles, squash mixture and sauce. Finish with a third layer of noodles, then cover with the remaining sauce. Scatter the remaining 1/2 cup Parmigiano cheese over the top.
5. Bake on the center rack until the lasagna is bubbling and the top is lightly browned, about 35-40 minutes. Let it rest for 10 minutes before serving.