1/2 cup plus 3 tablespoons all-purpose flour
1 tablespoon baking powder
1/8 teaspoon kosher salt
6 ounces unsweetened chocolate
2 pounds chopped bittersweet chocolate, divided
6 tablespoons unsalted butter, cubed and at room temperature
2 1/4 cups plus 1 tablespoon granulated sugar
5 eggs, room temperature
1 1/4 cups plus 1 tablespoon walnuts, chopped
fleur de sel or flaky sea salt, for sprinkling
parchment paper, for lining the baking sheets
Preheat your oven to 350 degrees F. Whisk together the flour, baking powder, and salt and set aside. Melt 16 ounces of the bittersweet chocolate with the unsweetened chocolate in a medium pan over medium-low heat, stirring frequently. Set aside to cool while you prepare the rest of the recipe.
Beat together the butter and sugar for a few minutes, until it has the texture of wet sand. Add in the eggs, one at a time, scraping down the sides of the bowl as necessary. Add in the flour mixture, and mix on the lowest speed until just moistened, then beat in the melted chocolate, until just combined. The dough will seem very wet at this point, but it will come together.
Fold the walnuts and remaining 16 ounces of bittersweet chocolate into the batter. Refrigerate the dough for 15-30 minutes before scooping the cookies.
Use a 2-tablespoon sized scoop or two spoons to drop the dough onto the baking sheets (it will be too wet to actually handle with your hands), then sprinkle with a bit of fleur de sel or sea salt. Bake at 350 degrees F for 10 minutes or so. Allow to cool completely before removing from the sheets. Also delicious warm if you can't wait.