Preheat oven to 425°F and place a large sheet pan in the oven to preheat as well. Melt ¼ cup (half a stick) of butter. Add 2 tablespoons of olive oil.
Stir in seasonings. Set aside.
Cut the rounded edges off of opposite sides of your potato and then cut the potatoes into ¼ inch planks (I get three planks per potato). Place planks into a bowl of cold water.
Place a pair of wooden skewers or chopsticks on each side of your potato plank. Using a sharp knife, make horizontal (side to side) slices in the potato, very close together. The skewers will keep you from slicing all the way through.
Flip over your potato plank and make slices on a 45° diagonal, again very close together. Place potato in cold water and slice the rest of the planks.
Use paper towels or kitchen towels to dry your latticed potato slices. Carefully remove your hot sheet pan from the oven and spray lightly with nonstick spray.
Dip each of your dried potato planks into your seasoned butter and oil, flipping them over to get flavor everywhere. You could also brush your seasoned butter on each side. Place immediately on your hot sheet pan.
Bake at 425°F for about 12 to 15 minutes, or until the bottoms are getting crispy. Flip your potato slices over. Place back into the oven and bake for another 12 to 15 minutes, or until the potatoes are sizzly and crispy.
If you want them more crispy, place them under the broiler for one to two minutes.
Allow to cool on the pan for 5 minutes, then garnish with flaky sea salt and chopped fresh herbs, such as chives.