Preheat oven to 350 F / 180 C.
Combine flour, cocoa, baking powder, orange zest, cinnamon and
salt in a medium bowl. Mix thoroughly with a whisk. Combine
sugars in a separate bowl, pressing out any lumps with your fingers.
Set aside.
With an electric mixer, beat butter and margarine until creamy.
Add sugars and Grand Marnier, Beat on high speed about 1 minute.
Beat in egg white. On low speed, beat in flour mixture until
just incorporated. Gather dough with your hands and form into
a neat 10-inch/25cm log. Wrap with parchment and chill 1 hour.
Using a sharp knife, slice log into 1/4-inch/0.5cm rounds and
arrange on a parchment-lined cookie sheet. Bake 12 to 14 minutes,
rotating often for even baking.