Instructions

1. Add the flour, cocoa powder, powdered sugar and salt to the bowl of a food processor.
2. Pulse until combined.
3. Add in butter and pulse 7 times.
4. In a small bowl whisk together the egg.
5. With the motor running pour in the egg and let process until the dough forms together into a cohesive ball.
6. Scrape the dough from the bowl and place in a piece of plastic wrap and form into a disk and wrap tightly.
7. Using a rolling pin roll the dough out until it stretches to the corner of the plastic wrap to ensure a tight seal.
8. Refrigerate for at least 2 hours, but preferably overnight.