Heat the oven to 425°F (220°C). Line a baking sheet with foil if you want easy cleanup.
Scrub the potatoes clean and pat very dry. Set one potato on a cutting board and place a wooden spoon or chopstick on each side (these act as guards).
Slice the potato crosswise into thin cuts about 1/8 inch (3 mm) apart, stopping when your knife hits the spoon/chopstick so you don’t cut all the way through. Repeat with remaining potatoes.
In a small bowl, stir together the melted butter, olive oil, minced garlic, and chopped herbs.
Arrange the potatoes on the baking sheet. Brush the butter mixture over the tops, letting it drip into the slices. Season with salt and pepper, aiming some seasoning into the cuts.
Bake for 55 minutes, or until the centers are tender and the edges are crisp and deeply golden. Halfway through baking, brush on more of the butter mixture to encourage extra crisping.
Rest for 5 minutes, then serve hot. Optional toppings: sour cream, grated cheese, bacon bits, or extra fresh herbs.