Mix together sugar and butter until well combined, gradually add eggs one at a time making sure each egg is fully incorporated before adding another. Mix in vanilla extract and cocoa powder. In a separate bowl, sift together flour, baking powder, espresso powder and salt. Gradually add in flour mixture a cup at a time until well combined. Cover and refrigerate for 4 hours to overnight or place in an airtight freezer-safe container for up to 2 months.
To bake, preheat oven to 350º F. Line rimmed sheet pans with parchment paper and scoop 1-inch portions from refrigerated cookie dough. Roll into a ball and then roll in powdered sugar and place onto parchment paper lined sheets pans. Bake 10 to 12 minutes. Let stand on sheet pan for a few minutes before transferring to a wire rack to cool completely.
Notes
To use frozen cookie dough, first allow to thaw completely in the refrigerator.