Whisk flour, cocoa powder, baking powder, cinnamon and salt together in small bowl.
Beat butter and sugar in large bowl. Beat in egg and vanilla. Stir in flour mixture. Shape into disk; wrap in plastic and refrigerate 2 hours or overnight.
Heat oven to 350°F. Line two baking sheets with nonstick foil. Roll out dough on lightly floured surface to 3/8-inch thickness. Cut into shapes with mask cookie cutters. Cut out eyes with sharp knife or cookie cutter; reroll scraps. Place on prepared sheets. Bake at 350°F for 10 to 12 minutes or until dry to the touch. Cool on pans 3 minutes, then move directly to racks. Cool completely.
Mix sugar, egg whites and a scant 1/2 cup water in a large bowl. Beat 5 minutes until very smooth. Spread onto cookie; top with colored sugar. Let dry; add a second coat of icing and a different colored sugar. Finish with stripes or dots.