Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper.
- Carefully slice each potato crosswise into thin slices about 1/8 inch apart, stopping about 1/4 inch from the bottom to keep the potato intact.
- In a small bowl, combine softened butter, minced garlic, parsley, thyme, salt, and pepper.
- Place potatoes on the baking sheet and brush generously with garlic herb butter, making sure to get some butter between the slices.
- Bake for 40-50 minutes, brushing with more garlic herb butter every 15 minutes, until golden, crispy on edges, and tender inside.
- Optional: sprinkle grated Parmesan cheese over potatoes during the last 10 minutes of baking.
- Remove from oven and let cool slightly before serving.