The day before you want to bake, begin the dough.
Divide the butter in half, brown one half of the butter on a small saucepan, and add the other half to a stand mixer. Transfer the browned butter to small bowl and whisk quickly to let it cool down.
Add the sugars to the stand mixer and mix on medium to create a gravely mixture. Add in the mostly cooled brown butter and beat until smooth and fluffy, about 3-4 minutes on medium. Add the vanilla and eggs and beat on medium high until the dough is very fluffy and smooth, about 2-3 minutes more.
Add the flours, salt and baking powder into the stand mixer. Mix on the lowest setting until the dough is just combined. Add in the chopped 70% chocolate and stir until just combined.
Pour the two kinds chocolate chips into a small bowl.
Using a scale, portion out the dough into 6 portions, each weighing a little over 6 ounces. Dip the top of the cookies into the chocolate chips, smashing any chocolate chips into open crevasses. To avoid oven drama, make sure none are too close to the bottom of the cookie, we don't want the chocolate chips to melt onto the pan.
Place these cookies on a parchment-lined baking sheet and freeze for 12-24 hours, with 24 being preferable.
When the cookies are ready to bake, preheat the oven to 450°F. Position a rack to the top center of the oven.
Bake the cookies two at a time for 8-11 minutes, or until the bottoms are golden but the tops are not scorched. Remove from the oven and use any utensil to nudge the edges into perfect circles, although most won't need any help.
Sprinkle the top of each cookie with flakey salt, and let the cookies come to room temperature. Then transfer them to the fridge to cool an additional 2 hours, this helps them set and brings out the flavor of the dough, so you aren't just tasting warm chocolate chips!
When ready to eat, let them come to room temperature again (or keep them cool!) and serve!