1 cup soft butter
2/3 cup sugar
1 tsp vanilla
1/4 tsp salt
2 1/2 cups flour
1/4 cup cocoa powder
Mix first 3 ingredients until light and fluffy. Add flour and salt to the mixture. Blend until combined. Do not overwork dough.
Split batter in half. set one have aside. To the second half of the mixture add the cocoa powder . Roll first the white and then the cocoa mixture to overlap. Cut ends off of cookies so edges are straight. Place white strip on top of brown strip and cut in inch and 1/2 logs. Take two logs pieces and join together so that colors alternate. This can be done as many times as you wish. Other cookies can be rolled into cylinders to give a swirl effect. Chill for at least 1 hour.
Remove from refrigerator and cut slices from logs. Bake on cookie sheets at 350 degrees for 11 to 14 minutes.