Preheat the oven to 350°F (175°C) to prepare for baking. This ensures that your cookie fries will bake evenly and come out perfectly golden brown.

Combine flour, baking soda, cornstarch, and salt in a medium bowl. Whisk them together until well blended, creating a uniform mixture to elevate your fries.

Mix melted butter, brown sugar, and granulated sugar in a separate large bowl until smooth. This creates the sweet foundation for your cookie fries, ensuring a delightfully chewy texture.

Add vanilla extract, egg, and egg yolk to the butter mixture, stirring well. This helps blend in the flavors, giving a rich depth to each fry.

Gradually incorporate the dry ingredients into the wet mixture, stirring until just combined. Be careful not to overmix; you want a lovely, thick dough.

Stir in the chopped milk and bittersweet chocolates until evenly distributed throughout the dough. This is where the magic happens—every fry will be bursting with delightful chocolate.

Scoop and shape the dough into fry-like strips, about ½ inch thick, and place them on a lined baking sheet. Giving them space helps ensure even baking.

Top each cookie fry with extra chopped chocolate and a sprinkle of fleur de sel. This elevates their flavor and appearance, making them irresistible.

Bake in the preheated oven for 10-12 minutes, or until the edges are golden but the centers remain slightly soft. This allows for that perfect melt-in-your-mouth texture.

Cool on the baking sheet for about 5 minutes before transferring them to a wire rack. This step is essential for achieving that ideal crispy edge.