In a medium bowl, sift the flour, cocoa powder, baking soda, and salt. Set aside.
1 1/2 cups All-purpose flour, 1/2 cup Unsweetened cocoa powder, 1/2 tsp Baking soda, 1/2 tsp Salt
In a large bowl using a mixer, beat the butter, brown sugar, and sugar. Beat for 2 minutes on high speed, it will get pale in color and fluffy.
3/4 cup Unsalted butter, 3/4 cup Brown sugar, 1/4 cup White granulated sugar
Add the vanilla and egg. Mix on medium speed until combined. Add in the dry ingredients and mix on low speed until just combined. This will be a thicker cookie dough.
1 tsp Pure vanilla extract, 1 Large egg
Pour the sugar in a bowl big enough to roll the cookie dough balls in. Use a small cookie scoop to scoop the cookie dough. Roll each cookie dough ball in your hands so it is smooth. Then, roll each cookie dough ball in the sugar.
1/3 cup White granulated sugar
Prep a cookie sheet with parchment paper. Place the cookie dough balls on the cookie sheet ( all of them). Use a 1/4th teaspoon to press a hole 2/3rds down into the cookie dough ball. If there are any cracks, use your hands to press it back together.
Chill the cookie dough balls in the fridge for 1 hour. Preheat the oven to 350℉. Bake 12 cookie dough balls on the cookie sheet at a time. Bake for 9 minutes. Immediately press the 1/4th teaspoon into the holes again. Bake for 2 more minutes.
Let the cookies sit for 5 minutes on the hot tray before transferring to a cooling rack. Cool completely.