1. Remove both the dough from fridge, divide each dough into two.
2. Place one portion of each dough in wrap and refrigerate.
3. Roll out the other portion into a rectangle of 6"*4.5" with a thickness of 1/2".
4. Place the rectangle in a butter paper, fold it tight and refrigerate for 2 hours.
5. Repeat for the other flavour.
6. After 2 hours, remove vanilla rectangle from fridge and cut it into 9 equal strips, with each strip measuring 1/2"*6".
7. Refrigerate again. The strips must be firm when forming the pattern.
8. Repeat with the chocolate rectangle.
9. On a butter paper form the checker board pattern as shown in the pictures.
10. You get two blocks of dough, each measuring, 1 1/2"*1 1/2"*6".
11. One block will use 4 vanilla and 5 chocolate strips and the other block uses 5 vanilla and 4 chocolate strips.
12. Roll in the butter paper tightly and refrigerate until firm.
13. There are two more portions of dough in the refrigerator. Now remove those portions and roll them into individual squares measuring 6"*6".
14. Place the block with 5 chocolate strips in the middle of vanilla square and place the other block in the middle of chocolate square.
15. With the help of butter paper bring the sides together so that the sides meet at the upper centre of the block.
16. Press the seam so that it becomes smooth and seam less.
17. Cover with butter paper and refrigerate overnight.
18. Now you have two blocks, one covered with chocolate dough and the other covered with vanilla dough.
19. Next day, slice the block into 1/2" thick cookies with a sharp knife.
20. Preheat oven to 175C.
21. Arrange the cookies on a lined tray 1 inch apart. Bake for 7-9minutes.
22. Take care that the vanilla dough retains its colour.
23. Cool on wire rack and store in an airtight jar.
24. Serve and enjoy.