In a blender combine soaked and drained cashews, water, lemon juice, and nutritional yeast. Blend on high until smooth and season with salt and pepper to taste.
Place a large skillet over medium heat and add oil to the pan. Then add in 4 ½ cups of the hash browns and cook stirring occasionally for 5-7 minutes or just until they are tender. Place them in a bowl then add the onion and garlic to the pan. Cook onion and garlic for 5 minutes until tender and add them to the bowl with the potatoes.
Then pour the cashew cheese mixture over the potatoes and toss to coat. Pour that into a 8×8 pyrex dish. Bake for 15 minutes. While that bakes, place a skillet over medium high heat and add remaining 3 tablespoons of oil to the pan. Then add in remaining ½ cup of hash browns to the pan in separate pieces and fry them for a few minutes of each side until golden brown.
When casserole is done, add crispy potatoes on top and enjoy!