Preheat oven to 350. Line baking sheets with parchment or a silicone baking mat if you have either of those.

Cream together the butter and sugar until light an fluffy (1-2 full minutes). Beat in the egg and vanilla until well combined.

Whisk flour and cocoa powder together and then slowly add to the butter mixture by spoonfuls with mixer at low speed. Scrape down sides and bottom of bowl as needed.

Lightly dust rolling surface with coco powder or flour or a mixture of both. (I use cocoa powder). Roll dough about 1/4 inch thick. It helps to roll soft dough in between sheets of plastic wrap or parchment and then place them in the fridge for about 15 minutes (or the freezer for 5-10) until firm.

Cut out shapes and place on baking sheets. Bake for 8-10 minutes, until set. Sometimes it's hard to tell with chocolate cookies when they are done, so just watch for the dough to not look "wet" anymore and the edges should be holding their shape nicely.

Let cookies cool for 2-3 minutes and then use a spatula to place them on a cooling rack.