Start by washing and very thinly slicing your potatoes. I recommend using a mandolin as it makes getting thin slices much easier and faster. Also, slice the onion.
Arrange the potatoes in a baking dish. I used a 9 x 9 inch dish.
To a blender, add the coconut milk, nutritional yeast, veg stock, cashews (make sure you soak them overnight, or for 1 hour in boiling water before making the recipe), lemon juice, onion & garlic powder, turmeric, salt & pepper. Blend on high speed until very smooth and creamy.
Pour the liquid on top of the potatoes. Important: make sure that every potato slice is fully covered in the liquid. Any parts that are not covered may not fully cook.
Bake the gratin for 50-55 minutes at 400F.
Remove the from over, top with vegan parmesan, fresh thyme, and parsley, and enjoy!