Set the oven's temperature to 350°F (177°C). Put parchment paper or a silicone baking mat on the baking sheet. Set aside.

In a small bowl, combine the flour, cocoa powder, and baking soda. Set aside.

Butter should be partially melted in a small pan over medium heat. Once it is completely melted, remove it from the heat and whisk. Set apart for cooling.

Put the butter and sugar in a large bowl and stir to combine. Then, incorporate the egg and vanilla by adding them and stirring.

Add the flour mixture in two batches and whisk thoroughly after each addition.

Place the 52–53 gram (2 and 12 tablespoon) balls of dough on the baking sheet. The dough can also be divided into 10 equal pieces and formed into balls.

The cookies should be slightly set after baking for 8 to 11 minutes. Cookies shouldn't have a wet but soft top. They'll be too delicate to manage. To preserve their moisture, take the cookies out of the oven. Let them to cool for 10 minutes or until the bottoms of the cookies are sufficiently stiff. There will be some puffiness to the cookies. Using the back of a spoon, gently press the cookies.