These cookies should keep everyone happy for a few days.
In a large bowl, sift together flour, cocoa, salt, and cinnamon. Set mixture aside.
Use an electric mixer to cream butter and sugar until fluffy. Beat in eggs and vanilla.
Add flour mixture; mix on low speed until thoroughly combined. Divide dough in half; wrap in plastic. Chill at least 1 hour.
Heat oven to 350 degrees. On a floured surface, roll dough to 1/8 inch thick. Cut into desired shapes. Transfer to ungreased baking sheets; refrigerate until firm, 15 minutes. Bake for 8 to 10 minutes, until crisp but not darkened. Cool on wire racks; decorate as desired.
