Ultra-Crispy 15-Hour Potatoes

Quick Overview

These viral layered potatoes take time, but the payoff is an ultra-crispy exterior with a meltingly soft, buttery interior. Thinly sliced potatoes are layered with rendered fat, pressed in the fridge overnight, then fried to deep golden perfection.

• Prep time: 45 minutes
• Chill time: 12 to 15 hours
• Fry time: 15 minutes
• Servings: 6 (yields 12 to 15 squares)
• Calories: ~280 kcal per serving

Ingredients

• 3 lbs (1.3 kg) Russet or Maris Piper potatoes, peeled
• 1/2 cup (120 g) duck fat or beef tallow, melted (unsalted butter works as a substitute)
• 1.5 tsp fine sea salt
• 1/2 tsp black pepper
• 1/2 tsp garlic powder
• Neutral oil for frying (vegetable, canola, or peanut oil)
• Flaky sea salt for finishing

How to Make Ultra-Crispy 15-Hour Potatoes

1. Preheat your oven to 300°F (150°C) and line a standard loaf pan with parchment paper, leaving plenty of overhang on all sides.
2. Slice the peeled potatoes paper-thin using a mandoline slicer, aiming for slices about 1/16-inch thick.
3. In a large bowl, toss the sliced potatoes with the melted duck fat, sea salt, black pepper, and garlic powder until every slice is evenly coated.
4. Layer the potato slices neatly into the lined loaf pan, stacking them flat one on top of the other until the pan is packed full.
5. Fold the excess parchment paper over the top of the potatoes, then cover tightly with a layer of aluminum foil.
6. Bake in the oven for 3 hours, or until a cake tester or sharp knife slides through the center with zero resistance.
7. Remove the pan from the oven, let it cool at room temperature for 20 minutes, then place a second loaf pan directly on top of the potatoes.
8. Fill the top loaf pan with heavy cans or brick weights to compress the potato layers tightly.
9. Transfer the weighted pan to the refrigerator and chill for a minimum of 12 hours, preferably 15 hours, until completely cold and firm.
10. Lift the chilled, solid block of potatoes out of the pan using the parchment overhang and place it on a cutting board.
11. Slice off the uneven edges with a sharp knife to create a clean rectangle, then cut the block into 1.5-inch squares.
12. Heat 2 inches of neutral oil in a heavy pot or deep skillet to 350°F (175°C).
13. Fry the potato squares in small batches for 3 to 5 minutes, turning occasionally, until deep golden brown and completely crispy on all sides.
14. Drain the fried potatoes on a wire rack set over a baking sheet and immediately sprinkle generously with flaky sea salt.

Pro Tip

Do not skip lining the loaf pan with parchment paper on all sides, and do not rush the chilling step. If the potato block is not completely cold and firmly pressed through to the center, the delicate layers will split apart and dissolve into messy flakes the second they hit the hot oil.

Serving & Storage

Serve these crispy potato squares immediately while hot, paired with a garlic aioli, sour cream with chives, or alongside a seared steak. Store leftover fried squares in an airtight container in the fridge for up to 3 days, and crisp them back up in an air fryer or 400°F (200°C) oven for 8 minutes.

FAQs

Can I make 15-hour potatoes without duck fat or tallow?

Yes, melted unsalted butter or clarified butter (ghee) works as a great substitute, giving the layers a rich, milky flavor and a deep golden color.

Can I freeze the compressed potato block before frying?

Yes, after the 15-hour chill in the fridge, slice the block into squares, wrap them tightly in plastic wrap, and freeze for up to 1 month. Fry them directly from frozen at 340°F (170°C) for 6 to 8 minutes until golden and hot throughout.

Why are my potato layers splitting apart when I cut them?

This happens if the potatoes were undercooked during the initial bake or if they were not chilled long enough under heavy weight. The starches must fully gelatinize in the oven and then cool completely under pressure to glue the layers together.