1.
Add the butter to a small saucepan over medium heat.
2.
Stir frequently as it melts, then stir constantly once it begins to foam.
3.
Cook for about 4–6 minutes, until the milk solids turn deep golden brown and smell nutty.
4.
Transfer the butter to a heat-proof bowl and chill until thickened but not solid.
5.
In a medium bowl, whisk together the all-purpose flour, bread flour, baking soda, and kosher salt.
6.
Add the cooled butter to a stand mixer with the brown sugar, white sugar, eggs, egg yolk, and vanilla.
7.
Mix on medium speed for about 2 minutes, until lighter in color and fully combined.
8.
Add the flour mixture and mix on low until about 75% incorporated.
9.
Add the chopped dark chocolate and semi-sweet chocolate chips.
10.
Mix on low just until combined and no streaks of flour remain.
11.
Cover the bowl with plastic wrap and refrigerate for 24–72 hours.
12.
When ready to bake, let the dough sit at room temperature for about 1 hour.
13.
Scoop the dough into
14.
gram balls.
15.
Lightly press the tops into flaky salt.
16.
Cover and refrigerate the shaped dough while the oven preheats.
17.
Preheat the oven to 350°F.
18.
Place 3 cookies on each parchment-lined baking sheet, leaving at least 3 inches between them.
19.
Bake for 8 minutes.
20.
Rotate and swap the trays, then bake for another 6 minutes.
21.
Remove the trays and firmly bang them on the counter 2–3 times to flatten the cookies slightly.
22.
Return to the oven and bake for another 2–3 minutes, until lightly golden with darker edges.
23.
Bang the trays on the counter again after baking.
24.
Cool on the trays for 5 minutes, then transfer the cookies to a wire rack.
25.
Serve warm, with vanilla ice cream if desired.