Preheat your oven to 350°F (175°C) and line your baking sheets with parchment paper.

Cream together the softened butter, granulated sugar, and brown sugar until light and fluffy, about 3-4 minutes.

Beat in the eggs one at a time, then stir in the vanilla extract.

Whisk together flour, baking soda, salt, and espresso powder in a separate bowl.

Combine the dry ingredients with the wet mixture gradually, mixing until just combined.

Fold in the semi-sweet chocolate chips and chopped nuts, if using.

Scoop rounded balls of dough onto the lined baking sheets, spaced about 2 inches apart.

Bake for 10-12 minutes, or until the edges are lightly golden and the centers stay soft.

Cool on baking sheets for about 5 minutes before transferring to wire racks.

Serve warm or at room temperature.