In a stand mixer, whisk granulated sugar, brown sugar, and melted butter until smooth and fluffy.

Add egg, then egg yolk, mixing well after each addition.

Add salt, baking soda, and vanilla extract; mix to combine.

Add flour in two parts and fold in gently with a spatula. Do not overmix—stop as soon as no dry flour remains.

Gently fold in potato chips, milk chocolate, and dark chocolate.

Cover and chill dough for at least 4 hours or overnight.

Scoop dough onto a lined baking sheet (about 3 Tbsp per cookie).

Bake at 350°F (177°C) for 10–11 minutes until edges are golden but centers are slightly underdone.

Sprinkle with flaky salt, let cool 5 minutes, then transfer to a rack.