Instructions: Melt the butter and mix it with the sugar in a large bowl until the mixture is light and fluffy. Add the egg and vanilla extract and mix them in well. Mix the cocoa powder, baking powder, salt, and flour in a different bowl using a whisk. Mix the dry ingredients into the wet ingredients one at a time until a dough forms. Make a disc out of each half of the dough. Cover them with plastic wrap and put them in the fridge for at least an hour or two. Warm the oven up to 350F 175C and put parchment paper on a baking sheet. On a floured surface, roll out the chilled dough until it is about 1/4 inch thick. Cut out the shapes you want with cookie cutters and put them on the baking sheet that has been prepared. Put it in an oven that is already hot and bake for 10 to 12 minutes, or until the edges are set. Let the cookies cool for a few minutes on the baking sheet before moving them to a wire rack to cool all the way. Once the cookies are completely cool, you can use icing or sprinkles to make them look nice, or you can just eat them plain!