Sift the cocoa and powdered sugar together in a bowl.
Add the crumbs, mixing well
Add the butter and toss with a fork until the crumbs are completely coated.
Spray the bottom of the quiche pan and spread 2/3 of the crumbs (200 grams or 7 ounces) evenly over the bottom of the pan.
Distribute evenly against the sides of the pan.
Press them firmly against sides
and the remainder (160 grams or 5 2/3 ounces) on the bottom.