Preheat the oven to 350 degrees F.
In a high-speed blender, combine the cashews, nutritional yeast, half of the salt, and garlic powder to make a vegan parmesan. Blend on high until ground and well-combined. Set aside.
In a large cast iron pan over medium heat, combine the coconut oil, garlic cloves, onion, the remaining salt, and pepper. Stir for 2 minutes, or until fragrant.
Add the arrowroot powder and stir to combine (will be clumpy) for about 2 minutes. Next, add in the coconut milk and vegetable broth, whisking to combine, for 3-5 minutes, or until the mixture begins to thicken.
Remove from the heat and gently pour into a high-speed blender. Add in the nutritional yeast, paprika, ginger, and coriander, blending to combine. Taste and add more spices and/or nutritional yeast as desired.
Rinse and dry the cast iron pan and place the potatoes so they cover the bottom of the pan. Sprinkle with salt and pepper, then coat the layer with vegan parmesan. Keep layering in this pattern until you’ve used all the potatoes.
Pour the cheese mixture over the layered potatoes and add additional spices on top, if desired.
Bake for 1 hour, or until the potatoes are easily pierced with a fork. Allow to cool for 5 minutes, then top with vegan sour cream or chives (or both!) and serve.