Scrub the potatoes clean and pat them dry. Place each potato between two wooden spoons or chopsticks to prevent cutting all the way through. Carefully slice the potatoes into thin, even slices (about 0.125 inch apart) without cutting through the base.
In a mixing bowl, combine the melted butter, olive oil, minced garlic, chopped rosemary, thyme, parsley, salt, and black pepper. Stir until well mixed.
Place the sliced potatoes on a baking sheet lined with parchment paper. Using a brush or spoon, generously coat each potato with the herb butter mixture, ensuring that the butter seeps between the slices.
Bake the potatoes in the preheated oven for about 40-45 minutes, basting them with more herb butter halfway through. If you’re using Parmesan cheese, sprinkle it over the potatoes during the last 10 minutes of baking.
The potatoes are done when they are crispy on the outside and tender inside. You should see the edges of the slices slightly fan out.
Remove the potatoes from the oven and let them cool slightly. Garnish with additional fresh herbs before serving.