In a large mixing bowl, cream together the softened unsalted butter, granulated sugar, and powdered sugar until the mixture becomes light and fluffy, about 3-5 minutes. Incorporate the espresso powder, salt, and vanilla extract.

Gradually add the all-purpose flour to the butter mixture, blending it in slowly until just combined. Be careful not to over-mix, as this can lead to tough cookies.

Place the dough onto a sheet of plastic wrap and shape it into a disc. Wrap it tightly and refrigerate for at least 30 minutes.

Preheat your oven to 300°F (150°C). Line a baking sheet with parchment paper.

Once chilled, roll out the dough to about ¼ inch thick on a floured surface. Cut out shapes or slice into logs.

Transfer the cookies onto the prepared baking sheet and bake for 15 minutes or until the edges are lightly golden.

Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack.