Preheat oven to 180 Deg C. Spread a butter paper in a 13x9x2 inch baking pan.
In a large mixing bowl, with an electric beater beat oil, sugar, eggs, milk and vanilla essence for 2 minutes on medium speed.
In a separate bowl sieve together flour, cocoa powder, baking powder, baking soda, and salt. Add this mixture little by little into the wet mixture and keep blending.
Stir in the hot boiling water to the cake batter and mix well for few seconds. Now the consistency of the batter will be thin and watery. Pour the batter into the pan.
Bake for 30 to 35 minutes or until the knife inserted in the center of the cake comes out clean. Mine usually takes about 40 to 45 min.
Cool for 10 minutes and then remove the cake from the pan and cool it on a wire rack. Wait till it is completely cooled down before frosting the cake.