Combine almond milk, thyme, nutritional yeast, garlic powder, salt and pepper to a sauce pan and heat over medium heat.
Mix cassava flour and mushroom stock together in a different dish and mix thoroughly to remove lumps.
Once almond milk mixture is starting to simmer, add mushroom/cassava mixture and whisk to combine.
Whisk over low heat until sauce thickens and set aside until needed. If you find your sauce is not thickening, add some additional cassava flour or tapioca/arrowroot starch.
Preheat oven to 425F.
Remove the skin from sweet potatoes using a vegetable peeler.
Use a mandolin to slice sweet potatoes thinly and store in large bowl of water to prevent them from drying out and changing color. If you do not own a mandolin, you can also slice them with a large knife, making sure to get the thinnest slices possible.
Slice the ham as thinly as you can.
Add oil to the bottom and sides of the cast iron skillet to prevent sticking.
Layer the sweet potato and ham slices around the bottom of the pan (see photo above in blog post for example).
Add a layer of sauce on top of the sliced sweet potato and ham.
Continue alternating layers of potatoes/ham and sauce until all the ingredients have been added to the cast iron pan.
Once complete, cover the cast iron pan with tinfoil and bake for 1 hour.
After 1 hour, remove the foil and continue baking uncovered for another 30 minutes or until the potatoes are tender and starting to brown on top.
I provide ingredient substitutions and recipe variations to make it vegan or AIP in the blog post above.Step-by-step instructions and photos can also be found in the blog post above as well.