In a large mixing bowl, beat the room-temperature unsalted butter and granulated sugar until the mixture is light and fluffy, about 3-4 minutes.

Gradually add the espresso powder and a pinch of salt to the butter mixture, mixing until well combined.

Slowly sift in the all-purpose flour, mixing until a crumbly dough begins to form.

Gently fold in the dark chocolate chips and any optional nuts.

Wrap the dough in plastic wrap and refrigerate for at least 1 hour.

Preheat your oven to 350°F (175°C). Roll the dough into logs about 2 inches in diameter and slice them into ¼-inch thick rounds.

Place the cookie slices on a lined baking sheet and bake for 12-15 minutes or until the edges are lightly golden.

Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.