Brown the 220 g butter (2 sticks) in a saucepan until golden and nutty. Cool until slightly thickened but still pourable.
In a stand mixer, whip the cooled brown butter with the 200 g light brown sugar (1 cup) and 50 g cane or granulated sugar (1/4 cup).
Add 1 egg and 1 egg yolk and 2 tsp vanilla extract and beat until light and fluffy.
In a separate bowl, whisk together 240 g flour (2 cups), 1/4 tsp baking soda, 1/2 tsp baking powder, 1 tsp sea salt, and 1 ½ tsp cornstarch.
Add dry ingredients to the wet in batches, mixing just until combined.
Fold in 2 cups chocolate chips.
Chill the dough for 1 hour, then shape into stubby pyramid mounds. Chill again or freeze.
Bake at 350°F for 12–13 minutes from chilled, or 14–15 minutes from frozen.
Sprinkle with flaky salt and let cool on a wire rack (or sneak one warm—it’s worth it).