Please read all the tips provided above for a successful recipe.
To the bowl of a stand mixer, add the butter, cream cheese, sugars. Beat on medium-high speed until light and fluffy. This will take about 4 minutes.
Stop, scrape sides of the bowl resume on medium and add egg and vanilla.
Sift together cocoa powder, espresso powder, flour, cornstarch, baking soda, and salt in another bowl. Slowly add to cookie mixture and mix about 1 minute until just combined.
Remove chilled dough from refrigerator and using a 2 tablespoon spring-release scoop, scoop into even portions. Roll into a smooth ball between your palms. Place on the room temperature (not hot) baking sheet 2-inches apart.
Bake at 350°F for 10 to 11 minutes or until edges have set and tops are just set, even if slightly undercooked or glossy in the center. Do not overbake. They will firm up as they cool. Cool for 5 minutes on the baking sheet then remove to a wire rack to cool completely.
Cookies will keep airtight at room temperature for up to 1 week.