Add the butter, cream cheese, and sugars to the bowl of a stand mixer. Mix on medium-high speed until the mixture is light and fluffy. It will take about 4 minutes to complete this task.
Stop, scrape the sides of the cup, then return to medium and whisk in the egg and vanilla extract.
In a separate cup, sift together cocoa powder, espresso powder, flour, cornstarch, baking soda, and salt. Slowly pour into cookie dough and stir for 1 minute, or until just mixed.
Hand-stir in the chocolate chips.
Refrigerate dough for at least 30 minutes after covering it.
When you’re about to bake, preheat the oven to 350°F. Preheat the oven to 350 degrees Fahrenheit. On a half sheet plate, place a Silpat silicone mat.
Remove the chilled dough from the refrigerator and divide it into even portions with a 2 tablespoon spring-release scoop. Between your hands, roll into a smooth ball. Place 2-inches apart on a baking sheet at room temperature (not hot).
Bake for 10 to 11 minutes at 350°F, or until the edges have set and the tops are only set, even if the centre is slightly undercooked or shiny. Don’t overcook. As they cool, they will firm up. Cool on the baking sheet for 5 minutes before transferring to a wire rack to cool fully.
Cookies can be stored at room temperature for up to a week in an airtight container.