Preheat the oven to 450 F (230 C)
Wash and peel the potatoes. Cut them into 1/8” thick slices.
Add olive oil to a large baking dish.
Place the potatoes in it. Season with salt, pepper and oregano. Toss the potatoes with your hands.
Add about 2 cups of water to the baking dish
Slice the onions (thick) and place them on top of the potatoes.
Chop the garlic and add it on top.
Add chopped parsley and parmesan cheese
Place the baking dish in the over at 450 F (230 C) until the potatoes become soft, then lower the heat to 350 F (180 C).