In a medium bowl, whisk together 1 3/4 cups plus 1 1/2 tablespoons all-purpose flour, 1 cup plus 1 1/2 tablespoons cocoa powder, and 3/8 teaspoon baking soda. Set aside.
In the bowl of a freestanding electric mixer fitted with a paddle attachment, beat 1 cup unsalted butter on medium-low speed until smooth. Add 1 teaspoon kosher salt and continue to mix for another 15 to 30 seconds. Add 3/4 cup plus 1 tablespoon granulated sugar and mix for about 2 minutes, until fluffy. Use a rubber spatula to scrape down the sides and bottom of the bowl before adding the dry ingredients (from the first step) in 2 additions, mixing on low speed for 15 to 30 seconds after each, or until just combined. Be careful not to overmix, and just mix until the dough has come together!
Mound the dough on a work surface lined with wax paper and push it together until it forms a 6-inch square block. Place the dough between two pieces of wax paper. With a rolling pin, working from left to right, and begin to flatten it. Turn the dough 90 degrees and repeat — this will help prevent the dough from cracking as it is rolled. Roll out to a 1/8-inch to a 1/4-inch thick sheet (see baker's notes). If the dough gets too melty and soft, simply refrigerate it until it gets firm again. This dough tends to harden pretty quickly, so 10 to 15 minutes should do the trick!
Use round cookie cutters to cut and stamp cookies from the rolled dough. If necessary, push the trimmings together and re-roll. Arrange the cookies on sheet pans lined with parchment paper, leaving about a 1/2-inch between them (they won't spread out too much when baking). Transfer the cut cookies to the refrigerator and let chill for an hour before baking.
When the dough is chilled and you're ready to bake, position a rack in the center of the oven and preheat the oven to 325 (F).
Bake in the preheated oven for around 15 minutes, or until the cookies are fragrant with small cracks on the surface. Because the dough is so dark, it might be kind of hard to tell – look for small cracks on the surface! Set the pans on a wire rack and allow them to cool completely before frosting.