Sieve the flour and baking powder. Cream the fat and sugar, add egg, essence. Finally, add the flour and make a soft dough. Divide the dough into two portions and add cocoa powder in one portion. Roll the white dough and brown dough separately, place one roll upon another roll then roll it like a cylindrical bar, keep it in the fridge for 20 minutes till it becomes hard, cut into ¼” thick. Preheat your oven and bake at 190° C for 30 minutes.