In a large bowl with an electric handheld mixer (or in a bowl of a stand mixer fitted with paddle attachment) cream together butter, brown sugar and granulated sugar until light and fluffy, about 1-2 minutes.
1/2 cup butter, 1/2 cup light brown sugar, 1/2 cup granulated sugar
Add the eggs and vanilla. Mix until the batter has lightened in color, about 2-3 minutes. Scrape down the side and bottom of bowl as needed.
2 eggs, 1 teaspoon vanilla extract
In a separate bowl, whisk together the flour, cocoa powder, baking soda and salt until combined. With the mixer running on low speed, pour into wet ingredients. Beat on low until combined.
1 2/3 cups all-purpose flour, 1/2 cup unsweetened cocoa powder, 1 teaspoon baking soda, 1/4 teaspoon salt
If adding chocolate chips mix in now.
1 cup mini semi-sweet chocolate chips
The dough will be thick and sticky. Cover dough tightly and chill in the refrigerator at least 3 hours. Chilling is mandatory.
Remove dough from refrigerator and allow to sit at room temperature for 10 minutes. If the cookie dough is chilled longer than 3 hours, let it sit at room temperature for 20 minutes. This makes it easier to scoop and roll.
Preheat oven to 350 degrees. Line large baking sheets with parchment paper or silicone baking mats. Set aside.
Scoop and roll dough balls, about 1.5 tablespoons of dough each. Roll each ball very lightly in granulated sugar, then generously in the confectioners’ sugar. Place 3 inches apart on baking sheets.
3 tablespoons granulated sugar, 1/2 cup confectioners' sugar
Bake the cookies for 10-11 minutes or until edges appear set and the centers still look soft. Cookies should look puffed and crackled on top.
Cool cookies for 5 minutes on the baking sheet, and then transfer to a cooling rack to cool completely.