2 ounces semisweet chocolate chips – reserved for topping
Instructions
Line 2 large baking sheets with parchment paper. In a medium bowl, whisk together the all-purpose flour, bread flour, baking soda, baking powder, and fine sea salt.
In a large bowl with a hand mixer or in a stand mixer fitted with the paddle, beat the unsalted butter, light brown sugar, and granulated sugar on medium-high until pale and fluffy, 3–4 minutes. Scrape the bowl.
Beat in the vanilla extract. Add the eggs one at a time, then the egg yolk, beating on medium just until smooth after each addition, 1–2 minutes total. Scrape the bowl.
Add the dry ingredients to the bowl and mix on low until just combined and no dry spots remain, 20–30 seconds. Do not overmix.
Fold in the 10 ounces of semisweet chocolate chips until evenly distributed.
Portion the dough into 12 mounds, about 4 ounces (115 g) each. Place on a parchment-lined tray, press the remaining 2 ounces of semisweet chocolate chips onto the tops, cover, and chill until firm, at least 1 hour and up to 24 hours.
When ready to bake, preheat the oven to 375°F (190°C). Arrange a rack in the center. Space 6 chilled dough mounds on each prepared baking sheet, leaving 3 inches between them.
Bake one sheet at a time until the edges are deeply golden and the centers are set at the edges but still soft and slightly underbaked in the middle, 13–16 minutes, rotating the pan halfway. The tops should have glossy patches of melted chocolate and faint cracks.
Cool on the sheet for 10 minutes, then transfer cookies to a wire rack to cool until just warm or room temperature, about 15 minutes more.
Repeat with the second sheet. Store cooled cookies airtight at room temperature up to 3 days, or freeze up to 2 months.