For the Potatoes:

1. Preheat the oven to 400°F.
2. Place the potatoes and a generous pinch of salt into a large saucepan. Add enough water to cover the potatoes.
3. Place over medium-high heat and bring to a boil.
4. Reduce the heat to a simmer and cook for 15 minutes, or until the potatoes are tender when pierced with a knife. Drain the potatoes well.
5. Line a baking sheet with foil and place a piece of parchment paper on top (this prevents the potatoes from sticking). Spread the potatoes out on the baking sheet in an even layer.
6. With a potato masher, gently press each potato to slightly squish it. It’s OK if the potato insides pop out of the skins a bit – you want this for ultimate crispiness!
7. Drizzle the oil evenly over top and season the potatoes with salt and pepper.
8. Bake for 20-25 minutes, turning them over halfway through, or until the skins are crispy and golden brown. Scatter the manchego cheese over the potatoes during the last minute of cooking time.
9. Serve warm, garnished with chives or parsley, and alongside the romesco sauce.

For the Romesco Sauce:

1. In a blender or food processor, combine all the ingredients for the sauce. Pulse or blend until everything is smooth and creamy. You can leave the sauce a little chunky if you prefer, but I like a very smooth sauce.
2. This can be made up to a week ahead of time and stored in an airtight container in the fridge. Bring to room temperature before serving.