In a large bowl, beat together sugar, cocoa powder, espresso powder, and vegetable oil until smooth and shiny.
Add eggs one at a time, mixing well after each. Stir in vanilla.
In a separate bowl, whisk flour, baking powder, and salt.
Mix dry ingredients into wet ingredients just until combined. Dough will be thick and sticky.
Cover and refrigerate for at least 2 hours.
Preheat oven to 350°F (175°C). Line baking sheet with parchment.
Scoop about 5 g of dough, roll generously in powdered sugar, and place on sheet.
Bake for 12 minutes exactly.
Let cookies rest on pan for a few minutes before transferring.