Beat the yogurt, sugar and vanilla essence on high speed. Add the baking powder & baking soda and whisk it lightly. Allow to stand for 3 minutes - you will notice that the mixture has turned a little frothy. Add oil and mix well. add chocolate bits now and mix

add the flour in 3-4 parts mixing until all the flour is well incorporated. (i divide the mixture in two portions and baked it in 2 batches, you cld try it in single layer as well) the cake is baked in lower rack.

Pour it into the baking dish.Bake at 200 degree C for 10 minutes and reduce the temperature to 175 degree C and continue to bake for 25 minutes or till the skewer comes out clean.

When done, remove and allow to cool for 30 minutes before turning over a wire rack to cool further.

Prepare the ganache:

Heat the cream in a non-stick pan and bring it to boil.
Remove from the flame, add the chopped bournville chocolate and mix well to get a smooth mixture.
Cool to room temperature while whisking continuously. Use as required.(mine was little watery as i added around 1/2 cup of cream so i added some cocoa pwd along with pwd sugar)

Apply the ganche on cake ,add the second layer of cake...apply the ganche on top the cake cover the sides.your cake is ready...The More ganche u apply the yummy the cake..Enjoy ;)