Preheat your oven to 350°F (180°C) and align three oven racks.

In a large mixing bowl, beat 1 cup of unsalted butter until creamy, then add ¾ cup granulated sugar and ¾ cup light brown sugar, mixing until fluffy.

Mix in 1 extra-large egg, 2 teaspoons of vanilla extract, and 2 tablespoons of warm water until just blended.

In a separate bowl, whisk together 2 ½ cups of all-purpose flour, 1 teaspoon of baking soda, and 1 teaspoon of kosher salt. Gradually mix into wet ingredients.

Fold in 10 ounces of chopped bittersweet chocolate until evenly distributed.

Scoop out 12 equally sized dough balls and chill in the freezer for 15 minutes.

Bake in the preheated oven for 10-20 minutes, tapping the baking sheets halfway through.

Sprinkle with fleur de sel or sea salt right after baking, then cool on wire racks.