Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

Rinse the potatoes thoroughly, keeping the skins intact. Place a wooden spoon or chopsticks beside each potato while slicing every 1/8 inch down into the potato.

In a medium bowl, combine the melted butter, minced garlic, parmesan cheese, and parsley. Season with salt and black pepper to taste, then whisk until well combined.

Fan out the potato slices and brush the garlic butter mixture over the potatoes, focusing on getting it between the sliced layers.

Place the potatoes cut-side up on the lined baking sheet and bake for 30 to 40 minutes, brushing with more garlic butter halfway through.

Once baked, allow to cool for a couple of minutes. Drizzle with extra garlic butter and garnish with additional parsley before serving.