Mix Dry Ingredients: In a large bowl, whisk together bread flour, baking powder, baking soda, and kosher salt until evenly distributed.

Prepare Butter: Using cold butter, schmear it in the mixing bowl for just 15 seconds – don’t cream it. You want it loosened but not whipped.

Add Sugars: Add light brown sugar and granulated sugar to the butter. Mix briefly until butter is just coated with sugar, maintaining cold butter pieces.

Incorporate Wet Ingredients: Beat in eggs one at a time, then vanilla extract. The mixture may look separated – this is normal and expected.

Combine with Flour: Add all dry ingredients at once. Mix on low speed until just combined with a few flour streaks remaining. Don’t overmix.

Add Chocolate: Fold in hand-chopped bittersweet and semisweet chocolate until evenly distributed throughout the dough.

Portion Cookies: Weigh out 120g portions of dough using a 1/2 cup measure. Place on parchment-lined baking sheets.

Chill Dough: Freeze cookie dough balls for 1 hour or refrigerate overnight for best results.

Bake: Preheat oven to 375°F. Bake chilled cookies for 19 minutes, rotating halfway through. Centers should look slightly underbaked.

Cool: Let cookies rest on baking sheet for 10 minutes, then transfer to wire racks to cool completely.