Preheat the oven to 350°F.

Line large baking sheets with parchment paper.

In the bowl of an electric mixer, beat the butter, brown sugar, and corn syrup on medium-high speed until very well combined, pale, and fluffy, about 3 minutes. Add the egg and vanilla and beat until combined. Add the flour, baking soda, salt, and espresso powder and beat until just combined. Add in the chocolate chips. The dough should be thick and slightly crumbly.

Shape the dough into 2-teaspoon sized balls and place on the prepared baking sheets. Bake for 10 to 12 minutes, or until golden brown. Cool for 10 minutes

Place the cocoa and cookies in a large deep bowl and toss until completely coated. Return to the pans, tapping off excess cocoa. Dust with a fine coating of powdered sugar. Serve or store in an airtight container for up to 4 days.