In a medium bowl, whisk together 1 cup plus 2 tablespoons all-purpose flour, 1/2 teaspoon baking soda, 1/2 teaspoon baking powder, and 1 teaspoon kosher salt. Set aside.
In the bowl of a freestanding electric mixer fitted with a paddle attachment, combine 1/2 cup unsalted butter, 1/2 cup black tahini, 1/2 cup dark brown sugar, and 1/2 cup granulated sugar. Beat on medium speed until fluffy, about 5 minutes. Lower the mixer speed to its slowest setting and add 1 large egg, beating until fully incorporated. Add 1 large egg yolk and 2 teaspoons pure vanilla extra, beating until fully incorporated. Turn off the mixer and scrape down the sides of the bowl with a rubber spatula.
Turn the mixer back on to its slowest setting. Add the dry ingredients (from the 1st step) in three parts, beating until the dry ingredients are just incorporated into the dough. Add 1 3/4 cup Valrhona feves and continue mixing on low speed until just incorporated throughout the dough.
Line a sheet pan with parchment paper. Use a 3 tablespoon cookie dough scoop to portion out around 16 dough balls. Transfer to the sheet pan and cover with plastic wrap; transfer to the freezer to chill overnight.
Once you're ready to bake the cookies, center a rack in the oven and preheat to 325 (F). Line two sheet pans with parchment paper and transfer the cookie dough balls to the sheet pans, leaving at least 3 inches apart between each ball. Bake for 15 minutes — because the cookies are dark, it can be hard to tell when they're finished. You want the edges to look a little darker and drier than the center. Transfer to a wire rack and let the cookies cool to room temperature completely on their sheet pans.