Preheat the oven 375, Spray the bottom of 9x13 glass dish
Peel, wash and thinly slice the potatoes, I use a mandolin
Cut the ham in cubes
Layer as follows: first potatoes, next ham, cheese, 3 pats of butter, onion powder and pepper, continue layering in this manner ending with a layer of potatoes adding , the remaining cheese on top
Whisk the milk a soup together and pour over top of the casserole, add 3 pats of butter and some parsley
Cover with foil, place on a baking sheet in case of spillage, bake for 45 mins, turn up the heat to 425 remove the foil and bake another 15 mins or until bubbly and brown, remove from oven and allow to sit 10 mins to set.