The yield depends on the size of the cookie cutter used to make the shapes.
Sift flour, cocoa, salt, and cinnamon together into a bowl; set aside. Put butter and confectioners sugar in the bowl of an electric mixer fitted with the paddle attachment. Mix on medium-high speed until pale and fluffy, about 3 minutes. Mix in egg and vanilla. Reduce speed to low. Gradually mix in flour mixture. Wrap dough in plastic wrap. Refrigerate 1 hour.
Preheat oven to 350 degrees. On a lightly floured work surface, roll out dough to 1/8 inch thick. Transfer to a parchment-lined baking sheet. Chill in freezer 15 minutes.
Using a 2- or 3-inch X- or O-shaped cookie cutter or a template and a knife, quickly cut out shapes from dough (if dough begins to soften, chill it in freezer 3 to 5 minutes). Reroll and cut scraps.
Transfer shapes to baking sheets, spacing them 2 inches apart. Chill in freezer until firm, about 15 minutes.
Brush flour from shapes. Sprinkle with sanding sugar. Bake until crisp, about 8 minutes. Let cool completely on sheets on wire racks.