cake flour (equivalent to 1 cup minus 1 Tablespoon, or 120.5 grams) • bread flour (equivalent to 1/2 cup plus 1/3 cup, or 120.5 grams) • plus 1/8 teaspoon baking soda (2.5 grams) • baking powder (3 grams) • kosher salt (4 grams) • and 1/4 sticks unsalted butter (10 Tablespoons, or 141 grams), softened • brown sugar (1/2 cup plus 2 Tablespoons brown sugar, or 142 grams) • white sugar (1/2 cup plus 1 Tablespoon, or 113 grams) • large egg, at room temperature • vanilla extract (10 ml) • chocolate (60% cacao, or dark chocolate) (~280 grams) • Sea salt for sprinkling (optional, but highly recommended)