Preparation Steps

• Set two oven racks in the upper and lower third. Preheat the oven to 325°F and line two baking sheets with parchment paper.
• Lightly crush the potato chips with your hands to about pea-size pieces. Measure 2 cups for the dough and reserve 1/2 cup for topping.
• In a medium bowl, whisk together the flour, cornstarch, baking soda, and fine salt until evenly combined.
• In a large bowl, beat the softened butter with both sugars on medium speed until pale and fluffy, 2 to 3 minutes. Beat in the vanilla, then the egg, followed by the yolk, mixing just until glossy and smooth.
• Mix in about half of the dry ingredients on low speed. Add the chocolate chips and mix briefly to distribute. Add the remaining dry ingredients and mix just until a few flour streaks remain.
• Fold in the 2 cups of crushed potato chips with a spatula until no dry spots remain. Let the dough rest 15 minutes (or chill 20 minutes) to hydrate and reduce spreading.
• Scoop the dough into 1½-tablespoon mounds and arrange 2 inches apart on the prepared sheets. Gently press the tops into the reserved crushed chips and sprinkle each with a tiny pinch of flaky sea salt.
• Bake both sheets at once for 12 to 14 minutes, rotating the pans front-to-back and top-to-bottom halfway through, until edges are golden and centers look set but still pale.
• Cool cookies on the baking sheets for 5 minutes, then transfer to a wire rack to cool completely.
• Baker’s tip: Spoon-and-level (or weigh) your flour for best texture; too much flour makes cookies dry and cakey.