Method of Preparation :
Mix maida, baking powder and Baking Soda (Sodium bicarbonate) together and sieve 3 times in a filter.
Beat egg well till it foams up, add powdered sugar and sunflower oil. Add the Maida mix little by little and keep stirring in one direction preferably with a wooden ladle. Add milk in between. Finally add 1/2 tsp of Vanilla essence.
Pour equal quantity of the cake mix/batter into two separate containers, add and mix cocoa powder in one of them.
Pour the plain cake mix to the baking tin first, and then the cake mix with cocoa on top of it. Take a knife and cut across the batter from one end to the other to get the marble look. Preheat the oven to 350 F degrees / 180 C and cook the cake for 20-25 minutes till it is done.
If you don't have an oven, grease a pressure cooker with little butter or oil and pour in the cake batter as mentioned above. Close the lid without the washer. There is no need to keep the weight as well. Cook the cake on slow fire for 45 minutes till done.