Step 1

Add the flour, cocoa powder, powdered sugar and salt to the bowl of a food processor.

Step 2

Pulse until combined.

Step 3

Add in butter and pulse 7 times.

Step 4

In a small bowl whisk together the egg.

Step 5

With the motor running pour in the egg and let process until the dough forms together into a cohesive ball.

Step 6

Scrape the dough from the bowl and place in a piece of plastic wrap and form into a disk and wrap tightly.

Step 7

Using a rolling pin roll the dough out until it stretches to the corner of the plastic wrap to ensure a tight seal.

Step 8

Refrigerate for at least 2 hours, but preferably overnight.