Begin by thoroughly washing and drying your russet or sweet potatoes. Using a mandoline, slice the potatoes uniformly to about 1/8-inch thickness, ensuring even cooking throughout. Place the sliced potatoes in a bowl of cold water to prevent browning.

Once sliced, remove the potatoes from the water and pat them dry. Lay a sheet of parchment paper on a baking tray, and arrange the potato slices in a fanned-out, accordion shape, allowing for even heat circulation.

In a small bowl, combine melted butter, minced garlic, and freshly grated Parmesan cheese. Drizzle this mixture over your arranged potato fans while lightly salting between layers.

Preheat your oven to 425°F (220°C) and bake the potatoes for 20-25 minutes. After this time, rotate the tray and bake for an additional 10-15 minutes until golden brown and crisp.

Once removed from the oven, let your Garlic Parmesan Accordion Potatoes rest for 3-4 minutes. Sprinkle freshly chopped parsley on top before serving.