Mix together the flour and cocoa powder in a bowl and set aside.
In another bowl or electric mixer, cream/beat the butter and sugar together for about 5 minutes until light and fluffy.
Slowly add half of the flour-cocoa mixture and mix on low speed, slowly add the remaining flour-cocoa mixture until well incorporated.
Stir in the salt. The batter should be thick and doughy.
Remove the dough from mixer and form a ball with your hands.
Roll out dough to form a log of desired size, keep in mind that you will be slicing the log to about 1/4 inch thick slices.
Wrap log in plastic wrap and refrigerate until ready to bake - at least an hour can keep up to a week.
When ready to bake, preheat oven to 325-350 degrees Fahrenheit depending on your oven, and butter or spray a nonstick cookie sheet, or line with parchment paper.
Slice the log into 1/4 inch slices and bake for 12-15 minutes.
