Preheat your oven to 350°F (175°C).

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

Cream the softened butter, granulated sugar, and brown sugar until light and fluffy.

Add the eggs and vanilla extract to the butter mixture, then mix until well combined.

Gradually mix in the dry ingredients to the wet ingredients, stirring until just combined.

Fold in the semi-sweet chocolate chips and dark chocolate if using.

Drop rounded tablespoons of dough onto a baking sheet lined with parchment paper, spacing them about 2 inches apart.

Bake for 10-12 minutes or until the edges are golden.

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