To prepare 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 or food processor 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 a cream cheese. Transfer the cashew cheese to a zip-top bag or a squeeze bottle and set aside. Alternatively you could use this Cashew Cream Cheese or Tofu Ricotta .

Prepare the sweet potato filling
Place a steamer basket insert in a saucepan filled with about 2 inches of water. Bring the water to 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.

Prepare the sautéed greens
In saute pan on medium to high heat, add the leeks to the pan, moving around the pan allowing the sugars to be released until the onions are slightly golden and translucent, about 3-4 minutes. Add 1/4 cup water or vegetable stock to deglaze and pick up those sugars to caramelize the leeks. Add the mushrooms, garlic, and salt. 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 prepare the tomato sauce, in a blender or food processor, combine the tomatoes, onion, tomato paste, dates, garlic, and 1 cup water. 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.

Alternatively, you could use this Fresh Pomodoro Sauce.

Preheat the oven to 350°F.

Bring a large pot of water to a boil. Cook the pasta according to the instructions on the package. Drain thoroughly. Lay out the noodles on a wire rack or towel, making sure they are spread out and not layered on top of one another to avoid sticking.

To assemble the lasagna, in the bottom of a 9 × 13-inch baking pan that is at least 2 inches deep, spread 11/2 cups of the tomato sauce. Arrange a layer of 4 lasagna noodles on top, overlapping each noodle slightly with the one that was laid down before.

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 (if the cashew cheese is in a zip-top bag, just snip off one corner so you can pipe the cheese over the greens).

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 35-45 minutes. Let stand for 5 minutes before serving.

Serve hot with your favorite side salad.