Grease and line a 6 or 7 inch baking tin well. You can also just grease with oil and dust with flour. Preheat your oven at 180 C or 350 F.
Combine 1/2 cup oil, 1 cup curd, 3/4 cup sugar and 2 teaspoons vanilla extract into a mixing bowl.
Whisk well until the sugar dissolves and the mixture turns pale and creamy.
Place a sieve over the bowl and add 1 cup flour, 6 tablespoons cocoa powder, 2 tablespoons corn flour, 1/2 teaspoon baking soda, 1 teaspoon baking powder and a pinch of salt.
Gently raise the sieve and sift the dry ingredients into the wet mixture.
Gently cut and fold the dry ingredients into the wet mixture without over mixing. Add 2-4 tablespoons water if the batter is very thick
Pour the chocolate cake batter into the prepared tin. tap once or twice to release air bubbles.
Bake in the preheated oven for 35-45 minutes. Keep the pan in middle rack of the oven with both the rods on. Keep an eye after 35 minutes and once tester comes out clean or with very few crumbs, your cake is done.
Let the cake cool in the pan for 5 minutes. Using a knife release the cake gently from the pan and cool in a wore rack completely.
Slice and serve as required. Store any leftover cake in airtight box in the refrigerator. Keeps well for 3-4 days.