Preheat the oven to 375°F and prepare cookie sheets by lining them with parchment paper.
Use a stand mixer (or handheld electric mixer) to cream the butter and brown sugar together in a large bowl.
1 cup salted butter, 2 cups light brown sugar
Then beat in the eggs, one at a time, and add the vanilla.
2 large eggs, 2 teaspoon vanilla extract
In a separate bowl, whisk together the flour, cocoa, baking soda, baking powder, and salt.
2 cups all-purpose flour, ¾ cup unsweetened cocoa powder, ½ teaspoon baking soda, ½ teaspoon baking powder, ½ teaspoon salt
Stir the flour mixture into the butter mixture until just combined.
Using a small cookie scoop, drop the batter evenly spaced apart onto your baking sheets.
Bake for 8 to 10 minutes.
Remove from the oven. While still warm, if your cookies are a little plump, you can use a spatula to gently press them down and flatten them to recreate a nice even surface for your frosting.
Place the cookie sheets on a cooling rack for about 10 minutes to allow them to cool completely.