Preparation Steps

• Preheat oven to 400°F. Toss the cubed butternut squash with olive oil, 1 teaspoon salt, and 0.25 teaspoon pepper on a sheet pan. Roast until tender and lightly caramelized, about 25 minutes. Reduce oven to 375°F.
• Make the sage béchamel: In a large saucepan over medium heat, melt the butter. Add onion and cook until soft, about 5 minutes. Stir in garlic and sage and cook 1 minute until fragrant.
• Sprinkle in the flour and cook, stirring, 1 minute. Slowly whisk in the milk until smooth. Simmer, whisking often, until thick enough to coat a spoon, 6 to 8 minutes. Stir in nutmeg and the remaining 0.5 teaspoon salt and 0.25 teaspoon pepper.
• Blend 3 cups of the roasted squash with the vegetable broth until very smooth. Stir the puree into the béchamel to make a creamy squash sauce. Reserve the remaining roasted squash cubes for layering.
• In a bowl, mix ricotta with 0.5 cup Parmesan until combined.
• Assemble the lasagna in a 9x13-inch baking dish: Spread 1 cup squash sauce on the bottom. Arrange a layer of noodles. Dollop one-third of the ricotta mixture, scatter one-third of the spinach and one-third of the reserved squash cubes, then sprinkle about 1 cup mozzarella.
• Repeat the layers two more times (sauce, noodles, ricotta, spinach, squash, mozzarella). Finish with a final layer of noodles, the remaining squash sauce, remaining mozzarella, and the remaining 1 cup Parmesan.
• Cover the dish tightly with foil (spray the underside with nonstick spray to prevent sticking). Bake at 375°F for 25 minutes.
• Remove foil and bake until bubbling and golden in spots, 15 to 20 minutes more. Let rest 10 minutes before slicing so it sets.
• Slice and serve warm. Garnish with extra chopped sage or cracked pepper if desired.