Combine butter and sugar in a large bowl (or the bowl of a stand mixer) and use an electric mixer to beat until creamy and well-combined.
Add egg and stir well.
Stir in extracts.
In a separate, medium-sized bowl, whisk together flour, cocoa powder, baking powder, and salt.
Gradually add dry ingredients to wet, stirring until well-combined (be sure to scrape the sides and bottom of the bowl so that all ingredients are evenly incorporated).
Divide the dough into two parts and form each into a disk, flattening each to about 1" thick. Cover in plastic wrap and chill for at least 1 hour.
Once dough has chilled, preheat oven to 350F (175C) and prepare cookie sheets by lining with parchment paper. Set aside.
Transfer dough to a clean, lightly floured surface and sprinkle flour over the top. Use a rolling pin to roll dough to about 1/8-1/6" thickness (yes, you want it to be pretty thin!).
Using a 1 3/4" round cookie cutter and cut out circles, transferring each to cookie sheet (the cookies won't spread so you can place them about 1/2-1" apart).
Once you have cut out all of the circles that you can, be sure to re-combine the scraps and roll out and cut out again to get the maximum number of cookies from your dough.
Bake on 350F (175C) for 8-9 minutes and allow cookies to cool completely before dipping.