Cook lasagna noodles until al dente. Set aside.
Saute onions over medium heat until slightly caramelized. Add a little water to deglaze the pan. Set aside.
Cook potatoes until soft. Mash with vegetable broth, yogurt, salt, pepper, and parsley. (I use a ricer to mash the potatoes and then stir in the remaining ingredients.) Set aside.
Combine vegetable broth, cashews, nutritional yeast, paprika, and salt in a blender and blend until smooth. Set aside. Saute onions over medium heat until slightly caramelized. Add a little water to deglaze the pan. Set aside.
Preheat oven to 350 degrees F.
Pour 1/2 cheese sauce into a 9x13" baking dish.
Layer 6 lasagna noodles over the cheese sauce.
Layer half of the mashed potatoes over the noodles.
Layer half of the onions over the potatoes.
Pour 1 cup cheese sauce over the onions.
Repeat with another layer of noodles, then remaining potatoes, then remaining onions, and then remaining cheese sauce.
Bake for 30 minutes or until bubbly. Let sit for 10-15 minutes before serving.