pieces of parchment paper. keep aside or preferably in the refrigerator.
take out the plain butter dough block and divide into 4 strips and roll out one strip to a 6 by 7 inch rectangle in between 2 pieces of parchment paper (keep the remaining strips refrigerated).
peel off the top pieces of parchment paper from both of the rolled out pieces of dough. flip the plain dough over the chocolate dough. peel off the parchment paper from the plain dough. trim the edges to get a neat rectangle.
gently by using the aid of bottom parchment paper roll up the layered dough into a nice tight log. wrap in cling film and 