Take softened butter,sugar,vanilla essence in a bowl.Beat till fluffy. Add the egg yolks one by one. Mix.

Next mix baking powder and flour and add to the butter and egg mixture. Beat it.

Mix cocoa powder and hot water together. Keep it aside.

On a dusted surface,knead dough for 2 mins.Cut into 2 halves.In one portion of the dough add the cocoa mixture and knead till everything comes together.

Refrigerate the doughs for 1 hours.

After that roll the doughs into thick rectangles.

Flip one rectangle on top of the other and roll them together into a tight log.

Refrigerate the log for 1 hour and cut into thick slices and bake them at 180'c for 10 -12mins.