Spray the center of the pan.
Combine flours, cocoa and baking powder in processor bowl.
Mix briefly to combine. Add butter and cut in until very fine.
Process briefly to mix. Add egg and egg yolk
Process until a ball forms.
Divide the dough in half.
Divide one of those pieces in two. Roll each piece into a 16 inch roll.
Lay along the bottom inside edge of one half the pan. Repeat with the other piece, overlapping the edges.
Press firmly against the edge of the pan.
Use the remaining half to cover the bottom of the pan.
Be sure to seal the seam well where the edge and the bottom meet
so it does not crack when baked.
Dock the crust with a fork.