Healthy Veggie Lasagna: Non-Meat Main

Butternut Squash, Oyster Mushroom, and Swiss Chard Lasagna

Ingredients

¼ cup olive oil

• ¼ cup olive oil, divided
• 1 lb. oyster mushrooms, roughly chopped
• Kosher salt
• 1 lb. Swiss chard, leaves removed from stems to yield 8 to 9 ounces, roughly chopped
• 1 quart of the butternut squash sauce 
• 12 sheets no-boil lasagna noodles
• 4 ounces Parmigiano-Reggiano, grated (about 1 cup)
• 8 ounces low-moisture, whole milk mozzarella, pulled into small pieces

Instructions

1. To make the sauce: Heat the olive oil in a 5- to 6-quart heavy pot over medium heat. Add the onion and sauté until softened, about 5 minutes. Add the cubed squash, 2.5 cups water, and 1 teaspoon salt. If your squash pieces are not submerged in water, add more water just until they are barely covered. Simmer, uncovered, stirring occasionally, until squash is very tender and water has reduced considerably, about 15 to 20 minutes depending on the size of the squash pieces.
2. Transfer mixture to a food processor or blender and purée until smooth. (Alternatively, use an immersion blender.) Taste sauce. Add more salt if necessary. Transfer to a bowl or storage vessel—you should have 1 quart of sauce. 
3. To make the lasagna: Heat the oven to 375°F. Heat 2 tablespoons of the olive oil in a large skillet over high heat. When it shimmers, add the mushrooms and let cook undisturbed for 2 minutes. Season with salt, then stir. Cook for another 2 minutes or until the mushrooms are cooked and browned at the edges. Transfer to a bowl to cool. Return the skillet—no need to wash it—to the stovetop over high heat and add the remaining 2 tablespoons of olive oil. Add the Swiss chard leaves and let cook undisturbed for 1 minute. Season with salt. Use tongs to rearrange the leaves and encourage them to wilt. Cook for 1 to 2 minutes more or until the leaves have collapsed. Transfer leaves to a bowl to cool. 
4. To assemble the lasagna: Spoon ½ cup of the butternut squash sauce into the bottom of a 9-by-13-inch baking dish. Top with three sheets of the lasagna noodles. Spread a scant ½ cup butternut squash sauce over the noodles. Spread ⅓ of the mushrooms and ⅓ of the Swiss chard leaves over top. Spread about ¼ cup of Parmesan over top, then ¼ cup mozzarella. Repeat this layering until you have topped the third layer of noodles with the last of the mushrooms and Swiss chard, ¼ cup of each of the cheeses, and a scant ½ cup of butternut squash sauce.
5. For the final layer of noodles, bring a small pot or kettle of water to a boil. Pour it into a small vessel such as an 8-inch baking dish. Submerge the remaining 3 noodle sheets into the water and let sit for 2 to 3 minutes, using tongs to occasionally rearrange the noodles to ensure they are not sticking together. (Note: This step ensures this final layer of noodles, which might not be surrounded by as much moisture as the bottom three layers, will soften and expand properly once in the oven.) Use tongs to remove each sheet of noodles and transfer to the pan. Spread the remaining sauce—it should be about ½ cup—over top, then top with the remaining cheese. 
6. Cover the pan with foil and refrigerate for up to 24 hours or transfer to the oven and bake for 40 minutes. Remove foil, and bake for 10 to 20 minutes more or until the cheese has melted and the top is bubbly and evenly golden. Let cool for 10 minutes before serving.