In a mixing bowl, sift together the flour and the salt and set aside.
In a separate larger bowl, using your hand held mixer, blend together the butter, sugar, and vanilla. Add the egg and beat until a smooth consistency.
Continuing to use your mixer, but on the lowest setting, mix in the dry ingredients.
Separate the cookie dough into two separate amounts.
Take one half, form into a large ball and then flatten to a disk shape with the palm of your hand. Wrap the dough in plastic wrap and set aside.
Add the cinnamon and cocoa powder to the remaining cookie dough, and using your mixer on a low speed, mix the powders into the dough.
Again, form the cinnamon-flavoured dough into a ball, flatten to a disk shape with the palm of your hand, and wrap in plastic wrap.
Place both packages of wrapped dough into your refrigerator for one hour.
After an hour has passed, retrieve one of the dough packages and roll to ¼ inch thickness (try to get as close to a rectangular shape as possible). Set aside.
Repeat with the next package of dough.
Gently lay one rectangular dough on top of the other. Carefully roll up the sides of the dough together so that a large log is formed. Wrap in plastic wrap and refrigerate once again for one hour.
Preheat oven to 350 degrees.
Slice the dough log into ¼ inch slices. Place each slice on a silicone or parchment lined baking sheet. Leave room between each slice for expansion.
Bake, one baking sheet at a time, for 12 minutes.
Allow cookies to cool on the baking sheet for two minutes before transferring to a cooling rack to finish cooling.