Preheat oven to 350°F (175°C) and prepare your cookie baking sheet by lining with parchment paper.
In a large bowl, use a handheld or stand mixer to cream together the butter, brown sugar, and granulated sugar until light and fluffy.
Beat in the eggs, vanilla extract, and finely ground espresso, mixing until smooth.
In a separate bowl, whisk together the flour, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Fold in the optional dark chocolate chips, if using.
Scoop cookie dough onto the prepared cookie baking sheets. Make them approximately tablespoon sized, and space them roughly 2 inches apart.
Bake at 350°F for 10-12 minutes, or until the edges are golden brown.
Carefully remove from the oven, then cool on the baking sheet for 5 minutes. Now they are ready to enjoy while they are warm & delicious!