Heat the vegan butter or olive oil in a skillet over medium heat. Add the sliced onions and cook, stirring occasionally, until they become beautifully caramelized, around 10-12 minutes.

Stir in the minced garlic, dried thyme, salt, and black pepper. Cook for another minute, allowing the garlic to release its aromatic flavor.

Add the balsamic vinegar or red wine, cooking until the liquid reduces slightly, about 2-3 minutes.

Blend the soaked raw cashews, broth, lemon juice, nutritional yeast, Italian seasoning, miso, and black pepper until smooth in a blender.

Mix in the sliced mushrooms to the skillet, cooking until they are softened, about 4-5 minutes.

Combine the creamy cashew sauce with the onion and mushroom mixture in the skillet, stirring until everything is well mixed.

Break the lasagna sheets into pieces and add them to the skillet, followed by the fresh spinach. Stir gently to combine.

Pour in the additional broth or water needed to cook the pasta and sprinkle with red pepper flakes if desired. Cover and simmer for about 10-12 minutes, or until the pasta is tender.