Place a rack in the center of the oven and preheat to 450 degrees F. Line a rimmed baking sheet with parchment paper or a silicone baking mat.
Place the olive oil, butter, and minced garlic in a small saucepan and heat over medium-high. Swirl the pan and once the butter is nearly melted whisk constantly; as soon as the butter is completely melted and the garlic is very fragrant, remove from the heat and whisk 15 seconds more. Stir in 2 teaspoons of the salt, the smoked paprika (if using), and the black pepper.
Place a potato on a cutting board and lay wooden spoon handles or chopsticks on either side. Cut the potato into very thin slices (about 1/8 inch), leaving a 1/4-inch uncut on the bottom so the potato stays intact. Transfer to the prepared baking sheet and repeat with remaining potatoes, leaving a little space between each.
Use a pastry brush to brush the butter mixture in between each potato slice and over the top, mopping up any butter that seeps onto the pan and brushing it back onto the potatoes. Discard any remaining cooked garlic left in the pan if desired.
Bake until the potatoes are crisp on the outside and fork tender inside, about 45 to 55 minutes depending on size, rotating the pan 180 degrees halfway through if they are not roasting evenly. As soon as the potatoes come out of the oven, season with a pinch of additional salt and the fresh herbs, then let cool a few minutes.