Preheat the oven to 300°F (150°C). Line a baking sheet with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment on medium speed, beat the butter, brown sugar, and granulated sugar until the mixture is fluffy, 30 to 60 seconds.
Beat in the egg and vanilla and mix until well combined, 30 to 60 seconds.
In another bowl, sift together the flour, baking powder, baking soda, and salt. Add the dry ingredients to the mixer, reduce the mixer speed to low, and beat until combined, 15 to 30 seconds.
Add the chocolate chips and espresso powder and mix for 15 seconds more.
Using a 1-ounce scoop, or using a 2 tablespoon measure, drop the cookie dough onto the parchment in dollops about 3 inches apart. Gently press down on the dough with the back of a spoon to spread out into 2-inch circles; there should be room for 6 or 8 cookies at a time.
Bake for about 20 minutes, until the cookies are nicely browned around the edges.
Place the baking sheet on a wire rack to cool slightly. Transfer the cookies to the rack to cool completely.