Directions

1. In a medium bowl, stir together the flour (all-purpose or oat) and salt. Add the butter (melted or chilled) and work the mixture into a dough. If making the first version with chilled butter, press the flour and butter together with your fingers, also working it into a dough. Add the sugar and vanilla extract and mix until combined. This can also be done using a food processor.
2. Divide the dough in half, leaving one half in the bowl. Add the cocoa powder and mix until the cocoa is fully incorporated. Divide each dough in half again so that you have 4 total, then roll each into a 8-inch log. Stack them into a chessboard (checkerboard) pattern, pressing and rolling them slightly together. Once they seem secure, press the chess log into a long rectangle, 1½ to 2-inch thick. Wrap it in plastic wrap and refrigerate until mostly firm, 30 to 45 minutes.
3. In the meantime, preheat the oven to 400ºF/200ºC and line a rimmed baking sheet with parchment.
4. Cut the chess cookies into ¼-inch thick slices, then place at least two inches apart on the prepared baking sheet. In batches, bake the cookies until golden brown, 7 to 9 minutes. Let them cook slightly before removing them from the pan.