Preheat the oven to 450F. Place a 9” cast iron skillet in the oven while it’s preheating. A small baking sheet, casserole dish, or pie dish can be used instead - if not using cast iron, no need to preheat the dish/baking sheet.

Cut roughly ⅛” slices in each potato, being careful not to slice all the way through, but as close as possible. You want the potato to be able to fan out with all the slices still connected at the bottom. Two chopsticks can be used as a buffer on the long sides of the potato to prevent the knife from going all the way through. It can also be helpful to slice a thin piece off the underside of the potato to allow it to lay flat on the cutting board.

Place the sliced potatoes in the preheated cast iron skillet (or baking sheet/casserole dish). Brush with melted butter and season with salt and pepper. Bake for 60 minutes, brushing with more butter every 15 minutes.

Make the pesto by combining all pesto ingredients in a food processor, and run it for 30 seconds or until broken down and saucy.

During the last 8 or 9 minutes of cooking time, spread some of the pesto over the potatoes and return to the oven to finish cooking.

Serve each potato with a good slather of cilantro pesto and chopped serrano pepper.