300 grams unsalted butter
150 grams powdered sugar
1/2 teaspoon salt
400 grams flour
40 grams chocolate powder
2 egg whites
In mixing bowl, cream together unsalted butter and powdered until light and fluffy. Reserve half the mixture in one mixing bowl. This will remain your “white” dough. To one half, add in the chocolate powder. Divide the flour and salt. Mix in the salt and the flour to each bowl. Wrap in plastic wrap and chill in refrigerator for 2-3 hours or until hard enough to roll out.
Separate the eggs, discarding the yolks or saving for another purpose. Split the chocolate dough into 3 balls and repeat with the plain dough. Roll out one third of the chocolate into a 1/4 inch thick surface. Roll out an additional ball of chocolate and the same amount of white dough, to approximately 1/2 inch thick.
Using a knife, make long strips in the thicker two sets of dough, approximately 1/2 inch wide. Brush the thinner dough with egg white (to use as glue). Place the long threads on the thin piece of dough, alternating white-dark-white, on top of that dark-white-dark and then again white-dark-white, all the while brushing the structure with the egg white to keep it together. Roll the thin layer (the exterior) around the snake of threads and wrap in aluminum foil and chill in refrigerator for 2-3 hours. Repeat with remaining dough (I typically try to do one with white exterior and one with dark exterior).
Preheat over to 400F. Unwrap chilled dough. Slice with sharp knife into 1/4 inch thick slices. Place on cookie sheet lined with silpat or onto parchment paper.
Bake 12-14 minutes or until golden brown at the edges. Cool on wire rack.