Preheat the oven to 375°F (190°C). Lightly grease a 9"x13" baking dish.

Bring a large pot of water to a boil and cook the pasta according to the packaged instructions. Drain and set aside.

In the meantime make the alfredo sauce. Melt the vegan butter in a large pan. Add the onion and garlic and sauté, stirring occasionally until the onions soften and just begin to brown.

Sprinkle over the flour and stir to coat the onions. Keep stirring while cooking the flour for about 60 seconds. Add the plant-based milk, nutritional yeast, miso paste, salt, and pepper and whisk well. Cook, while whisking often until the sauce thickens, 5 - 10 minutes. Stir in 1 tablespoon of parsley and remove from the heat.

Spread the cooked pasta in the baking dish and pour over all of the alfredo sauce, stir to coat the pasta.

Softening the cashews (optional): Softening the cashews helps them blend. If you have a high-powered blender you can skip this step, but if not, this step is important to get a smooth mozzarella. You can either boil or soak the cashews. To boil the cashews (the fast method): add the cashews to a small pot, cover with water, and boil for about 10 minutes until the cashews are very tender. To soak the cashews: add the cashews to a bowl, and cover them with water. Let soak for 4 hours or overnight until tender. Drain and rinse cashews before using.

Add the cashews, plant-based milk, tapioca starch, nutritional yeast, vinegar, salt, and garlic powder to a blender and blend until completely smooth and creamy. Pour into a small pot and cook while stirring often. The sauce will start to get clumpy as it cooks, and then will turn into a gooey cheese sauce.

Remove from the heat and then dollop the mozzarella over the pasta. Use a spatula to spread it over the pasta.

Bake uncovered for 20 minutes or until the pasta is heated through. Optionally you can brown the mozzarella a bit by putting it under the broiler for a few minutes while keeping a close eye on it so that it doesn’t burn. Garnish with the remaining tablespoon of parsley and serve hot.