- Slice the potatoes into 1/4” rounds (leaving the skin on) with either a mandolin (see notes for the best mandolin!) or a sharp knife. Place the potatoes in a bowl of ice water and allow to soak for 30 minutes.
- Preheat the oven to 400F, rack in the middle. Line a rimmed baking sheet with foil and set aside.
- Drain the potatoes and then pat dry. Place the potatoes on the baking sheet in a single layer. Mix together the olive oil and butter then drizzle half of the mixture over top.
- Sprinkle 3/4 teaspoon of salt and parsley over top of the potatoes, flip the potatoes over and drizzle the remaining butter and oil mixture, salt and parsley.
- Bake for 20 minutes, remove the pan from the oven, flip the potato slices over carefully and bake for another 15-20 minutes or until the tops are crispy and golden brown.
- Remove from an oven and place on a paper towel lined pan to soak up any excess oil. Taste for seasoning.
- Serve with French Onion Sour Cream Dip!