- 1 tablespoon extra-virgin olive oil, plus more if needed
- 1 pound hot Italian sausage, casings removed
- 1 large yellow onion, chopped (about 1 ½ cups)
- 3 garlic cloves, minced
- 1 (1 ½-pound) butternut squash, cut into ½-inch dice (about 2 ½ cups)
- ¾ cups parsnips, shredded
- 2 (15-ounce) containers light ricotta (half skim)
- 2 large eggs
- 1 (10-ounce) package frozen chopped spinach, thawed and squeezed dry
- 1 teaspoon kosher salt
- ½ teaspoon cracked black pepper
- 2 cups shredded mozzarella cheese
- 1 cup shredded Parmesan cheese
- 1 cup fresh basil leaves, torn
- 6 cups store-bought or homemade marinara sauce
- 1 (8-ounce) package no-boil lasagna noodles
- Preheat the oven to 400º F.
- In a large skillet set over medium-high heat, heat the olive oil. Add the sausage and cook, breaking up with the back of a spoon, until browned throughout, about 5 minutes. Using a slotted spoon, transfer the sausage to a paper towel-lined plate. Add the onion and garlic to the pan, adding extra olive oil, if needed. Cook, stirring, for 1 minute before adding the butternut squash and parsnips. Cook for 8 to 10 minutes, until vegetables are tender. If the squash and parsnips start to stick to the pan, add 1 tablespoon of water. Season to taste with salt and pepper. Remove the pan from the heat and drain any excess liquid. Stir in the reserved sausage.
- In a medium bowl, whisk together the ricotta, eggs, spinach, salt, and pepper. Add the spinach and mix well.
- In a separate bowl, combine mozzarella, Parmesan, and basil.
- Spread 1/3 of the marinara sauce in the bottom of a 9×13-inch baking dish. Arrange a layer of lasagna noodles on top. Evenly distribute 1/3 of the ricotta mixture over the noodles, followed by 1/3 of the vegetable-sausage mixture. Then sprinkle with 1/3 of the shredded cheese mixture. Repeat to make two more layers, ending with shredded cheese mixture on top. The assembled lasagna can keep tightly covered in foil in the refrigerator up to 1 day before baking.
- Cover the dish with aluminum foil and bake for 30 minutes. Remove the foil and bake until the top is golden brown, about 15 minutes. Let cool for at least 10 minutes before serving.
- To make ahead and freeze, line the baking dish with aluminum foil, allowing for plenty of overhang. Assemble the lasagna, wrap tightly, and freeze for up to 1 month. The day before planning to serve, put the wrapped lasagna in the refrigerator to thaw overnight. Bake as directed.