Drain the soaked cashews and place them into a blender along with nutritional yeast, lemon juice, minced garlic, a pinch of salt, and water. Blend until smooth and creamy, adjusting with more water if needed to reach a velvety consistency. Set aside.
Heat olive oil in a saucepan over medium heat. Add chopped onion and sauté until translucent and fragrant, about 3 minutes. Stir in crushed tomatoes, salt, pepper, and a handful of fresh basil if desired. Let simmer gently for 20 minutes until the sauce thickens and develops rich aroma.
While the sauce simmers, sauté your chosen vegetables—mushrooms, zucchini, and spinach—in a skillet with a splash of olive oil until just tender and fragrant, about 5 minutes. Season lightly with salt and pepper. Remove from heat and set aside.
Spread a thin layer of tomato sauce at the bottom of your ovenproof baking dish. Place a layer of no-boil lasagna noodles over the sauce, slightly overlapping. Spread a layer of cashew cheese evenly over the noodles, then sprinkle with sautéed vegetables and a handful of shredded vegan mozzarella.
Repeat the layering process—noodles, cashew cheese, vegetables, cheese—until all ingredients are used, ending with a top layer of noodles covered with tomato sauce and a generous sprinkle of vegan mozzarella.
Bake the assembled lasagna in a preheated oven at 180°C (350°F) for 40–45 minutes, until bubbling around the edges and the top is golden brown. If the cheese begins to brown too quickly, tent the dish with foil to protect it.
Remove the lasagna from the oven and let it rest for at least 15 minutes. This helps the layers set and makes slicing easier. Garnish with fresh basil or herbs if desired.
