Preheat oven to 350 degree F.
Meanwhile, boil water in a pan and add the instant coffee to the boiling water.
Now take the chocolate chips in a bowl and pour the hot coffee water over them. Let it sit for around 2-3 minutes.
Using a whisk, mix the melted chocolate chips with hot coffee.
Now add melted butter, jaggery powder, vanilla extract, eggs and buttermilk to the chocolate chips mixture.
Whisk everything together till all the ingredients are uniformly mixed, will not take more than a minute. Wet ingredients mixture is ready.
Now add the dry ingredients (whole wheat flour, cocoa powder, salt, baking powder and baking soda) to the wet mixture. Mix everything together. I would recommend that if you are using electric mixer, beat it for 2-3 minutes on medium speed. If you are beating by hand using a whisk, you can beat everything for around 5-7 minutes.
Pour the batter into a 9 inch round greased and dusted cake pan and bake in pre-heated oven for around 30-35 minutes, or till the cake is done (when the toothpick inserted in the center comes out clean).
Once done, remove the pan from oven. Allow the cake to cool for around 5 minutes before removing it from pan.
Enjoy the healthy and delicious double chocolate whole wheat cake!