Sweet Potato Lasagna
FOR THE CASHEW CHEESE
1 cup cashews
1 ½ tablespoons nutritional yeast
2 tablespoons fresh lime juice (from 1 to 2 limes)
¼ teaspoon garlic powder
¼ teaspoon sea salt
¼ teaspoon freshly ground black pepper
FOR THE SWEET POTATO FILLING
3 pounds white-fleshed sweet potatoes (4 to 5 medium), peeled and cut into large pieces
1 tablespoon fresh lime juice (from 1 lime)
FOR THE SAUTÉED GREENS
2 cups finely chopped leeks, white and light green parts
12 ounces button mushrooms, finely chopped (4 cups)
2 small cloves garlic, minced
1 bunch Swiss chard, stemmed and finely chopped (about 4 cups)
1 bunch spinach, stemmed and finely chopped (about 4 cups)
FOR THE TOMATO SAUCE
3 medium tomatoes, diced (about 3 cups)
1 cup diced red onion
2 (6-ounce) cans tomato paste
2 pitted dates
2 cloves garlic
1 tablespoon dried oregano
1 tablespoon dried basil
1/8 teaspoon freshly ground black pepper
1 pound rice lasagna noodles (16 noodles)
To make the cashew cheese: Place the cashews in a small bowl and add at least 1 cup water. Set aside to soak until softened, 1 to 2 hours. Drain the cashews and place them in a blender with the nutritional yeast, lime juice, garlic powder, salt, pepper, and ¾ cup water. Blend until the mixture is smooth and has the consistency of cream cheese. Transfer the cashew cheese to a pastry bag, a resealable bag, or a squeeze bottle, and set aside.
Meanwhile, to make the sweet potato filling: Place a steamer basket insert in a saucepan filled with about 2 inches of water. Bring to a simmer, and add the sweet potatoes. Cover the pan and steam until tender when pierced with the tip of a sharp knife, 15 to 17 minutes. Transfer the sweet potatoes to a large bowl.
Use a potato masher to mash the sweet potatoes. Add the lime juice and salt to taste, and mix well. Set aside.
To make the sautéed greens: Combine the leeks and ¼ cup water in a sauté pan. Cover and cook over low heat until the leeks are very soft, about 15 minutes. Add the mushrooms, garlic, and salt to taste. Cook, covered, over medium heat, until the mushrooms are soft, 5 to 7 minutes. Add the Swiss chard and the spinach, and cook, uncovered, until the greens are tender, 5 to 7 minutes. Remove from the heat and let cool.
To make the tomato sauce: Combine the tomatoes, onion, tomato paste, dates, garlic, and 1 cup water in a blender or food processor. Blend until smooth. Transfer the mixture to a saucepan, and add the oregano, basil, pepper, a generous pinch of salt, and 2 cups water. Cook over medium heat for 40 minutes. Taste for seasoning and set aside.
Bring a large pot of water to a boil. Cook the noodles according to the instructions on the package. Drain thoroughly. Spread out the noodles on a wire rack or a towel, making sure they do not overlap. Let cool.
Preheat the oven to 350°F.
To assemble the lasagna, spread 1 ½ cups of the tomato sauce over the bottom of a 9 × 13-inch baking pan that is at least 2 inches deep. Arrange a layer of 4 lasagna noodles on top, slightly overlapping each of them.
Top with half of the mashed sweet potatoes, then another layer of 4 noodles. Spread all of the sautéed greens on top. Pipe half of the cashew cheese on top of the greens (if it is in a resealable bag, just snip off one corner).
Arrange a layer of 4 pasta noodles on top of the cheese. Spread half of the remaining tomato sauce over the pasta. Spread the remaining sweet potatoes on top.
Arrange the last layer of pasta atop the sweet potatoes. Spread the remaining tomato sauce on top. Pipe the remaining cheese over the sauce in a fun zigzag or swirling pattern.
Bake until the cheese on top is lightly browned and the sauce is bubbling along the sides of the pan, about 45 minutes. Let stand for 5 minutes before serving.