In a large bowl, mix together the dry ingredients - flour, cocoa powder, baking powder and baking soda.

In another bowl, beat well the butter and sugar.

Beat the egg very well in a different bowl and add the beaten egg to the butter sugar mixture.

Add the vanilla essence, mix well.

Add the butter sugar egg mixture to the dry flour mixture and mix well until all ingredients are mixed well, you may use your hands to mix the cookie dough if you can't do with a spoon.

Add the oil also and mix very well to form the cookie dough, mix again to make the perfect cookie dough.

Cover the dough and chill in the refrigerator for about 30 minutes. Now the chilled cookie dough is ready to be used.

Preheat oven to 350 degree Fahrenheit.

Keep the powdered sugar in a small bowl aside.

Make small balls (about 1 inch) out of the cookie dough and place them in the cookie sheet. The cookies will spread as they get baked so you need to leave some space in between the balls. You do not need to bake the entire cookies at the same time, as mostly they won't fit in a single cookie sheet. You can just use about half of the cookie dough to make about 12 cookies and do the remaining in the next batch (remember to chill the remaining dough until ready to use).

Once you have placed the cookies in the cookie sheet, take each of the balls, one at a time, and roll them in the bowl of powdered sugar so the ball is all covered in sugar, and place the rolled ball with sugar back in its place in the cookie sheet. Do the same for all the dough balls.

Bake for about 12 to 14 minutes and transfer the cookie sheet immediately from the hot oven in order to prevent the cookies from getting baked further.

Allow the cookies to cool down completely, once cooled, enjoy the delicious cookies with a cup of milk, tea or coffee! Similarly bake the remaining cookies (from the remaining dough) as well.