Preheat oven to 350 degrees Fahrenheit.

In the bowl of an electric mixer cream together the butter, sugar, salt and baking soda for 2-3 minutes on medium speed.

Add the egg white and mix until combined.

Whisk together the flour and cocoa and add to the butter mixture and beat on low until the flour mixture is just combined.

Divide the dough in half. Roll each half between 2 pieces of parchment paper to a thickness slightly thinner than 1/8”. Place both sheets of dough in the freezer for about 10-15 minutes.

Remove one sheet of dough from the freezer, peel off the top sheet of parchment paper, turn over and remove the other piece of parchment.

Cut the dough into 2 1/4” circles. You can gather together and reroll any leftover dough and continue to cut out cookies.

Place the cookies on a parchment lined baking sheet and bake for 11-12 minutes.  Remove from the oven and let the cookies cool for 10 minutes.  Transfer the cookies to a wire rack and allow to cool completely.

Makes about 25 cookies.