Why I Love This Recipe: This lasagna can be assembled the day ahead and stored in the fridge until you're ready to bake it, so it's perfect for busy cooking days like Thanksgiving. It is one less thing to have to put together for Thanksgiving dinner!
Technique Tip: Whisk the béchamel constantly while adding the milk to the sauce to avoid lumps.
Swap Option: Any winter squash can be substituted for the butternut squash in this recipe. Canned pumpkin would even work.
- In a small bowl, mix together the breadcrumbs, Parmesan and olive oil. Set aside.
- Heat the oil in a heavy large skillet over medium-high heat. Add the squash and toss to coat. Sprinkle with 3/4 teaspoon salt. Pour the water into the skillet, then cover and simmer over medium heat until the squash is tender, stirring occasionally, about 15 minutes. Cool slightly, then transfer the squash to a food processor. Add the amaretti cookies and blend until smooth.
- Melt the butter in a heavy medium-size saucepan over medium heat. Add the flour and whisk for 1 minute. Whisk in 1/2 cup of the milk until smooth. Continue whisking as you pour in the remaining milk. Bring to a boil over medium heat and simmer until the sauce thickens slightly, whisking often, about 5 minutes. Whisk in the pesto, pecorino and the nutmeg. Season with 1/2 teaspoon salt.
- Position the rack in the center of the oven and preheat to 375 degrees F. Lightly butter a 13x9x2-inch glass baking dish. Spread 3/4 cup of the sauce over the prepared baking dish. Place 4 lasagna noodles on the sauce. Spread one third of the squash puree over the lasagna noodles. Sprinkle with 1/2 cup of mozzarella cheese. Drizzle 1/2 cup of sauce over the noodles. Repeat layering three more times, finishing with a layer of noodles and sauce. Top the lasagna with the remaining mozzarella cheese and sprinkle with the breadcrumb mixture.
- Tightly cover the baking dish with foil and bake the lasagna for 25 minutes. Uncover the lasagna and continue baking uncovered until the sauce bubbles and the top is golden,
- 25 minutes longer. Let the lasagna stand for 15 minutes before serving.