Stuck in a lasagna rut? Snap out of the usual red-sauce routine with this divine lasagna.
*If you are not using a high-powered blender, such as a Vitamix, soak cashews or almonds overnight or boil for 10 minutes and drain. This will soften them and ensure a silky smooth cream.
For the roasted butternut squash: Preheat the oven to 400°F. Spread butternut squash on a large rimmed baking sheet and toss with oil. Season with salt and roast for 30 minutes, until fork-tender. Remove from oven and puree in a food processor until smooth. If needed, add 1 to 2 tablespoons of water.
For the spinach: In a large skillet, heat oil over medium heat. Add spinach and let cook until just wilted.
For the alfredo sauce: Heat oil in a medium skillet over medium-high heat. Add onion and let cook until soft. Remove from heat. In a blender, combine onion, garlic, cashews, water, lemon juice, salt, and pepper. Process on high until very smooth, about 2 minutes, and set aside.
MAKE-AHEAD TIP: Ricotta can be made the day before and stored in the refrigerator.
To assemble and bake the lasagna: Preheat the oven to 375. Lightly grease a 9 x 13-inch pan. Spread a thin layer of sauce on the bottom of the prepared pan. Arrange 4 lasagna noodles across the pan; it’s okay if they overlap a little. Layer half the ricotta, 4 noodles, sauce, butternut squash, spinach, sauce, 4 noodles, sauce, remaining half ricotta, and 4 more noodles. Top lasagna with remaining sauce, reserving about 1 cup for serving. Noodles should be evenly coated.
Cover the baking pan with foil and bake for 50 minutes, or until noodles are cooked through. Remove from oven and let rest for 5 minutes before serving. Top each serving with a generous spoonful of heated sauce.