How to Make It
Preheat oven to 325°F. Line 2 rimmed baking sheets with parchment paper. Set aside.
Beat sugar and butter together until lightened, about 2 minutes. Add corn syrup and mix to combine. Scrape down sides of bowl, add egg, and beat for an additional 2 minutes until fluffy.
In a separate bowl, sift together flour, cocoa powder, espresso powder, baking soda, and salt. Add to wet ingredients and mix on low until just combined, 1 to 2 minutes. Mix in chocolate until combined, 1 minute.
Place powdered sugar in a small bowl. Scoop out cookie dough in heaping tablespoon amounts and roll the cookie dough in your hands to create a ball. Place each ball, one at a time, in the powdered sugar and roll it around in the sugar until the dough is completely covered. Gently lift the cookie dough out of the bowl and place it on a prepared baking sheet. Repeat with remaining cookie dough, spacing the balls of dough about 3 inches apart.
Bake for 10 minutes, remove from oven and use a flat unspotted spatula to flatten each cookie by pressing down on the ball until it forms a 3 inch wide circle. Wipe the spatula with a paper towel between each cookie press, and return cookies to oven to finish baking for an additional 7 minutes. Allow to cool on baking sheet before serving. (Note: the cookies will fall apart if you try to remove them from the baking sheet before they have cooled slightly.)