Preheat oven to 170 degree C.Line two 8 inch pan with parchment paper and grease it well with flour. Set aside.
Take both sugar, water, oil, vinegar, vanilla, coffee, salt in a bowl and mix well. Mix till sugar melts.
Now add in flour, cocoa powder, baking soda, and mix well.
The batter will be little liquidy.
Now divide the batter between two cake pan and bake them for 25 to 35 mins till a toothpick inserted comes out clean.
Remove the cake from oven and set aside to cool completely.
You have to start the frosting when the cakes are baking.
Take water, brown sugar and butter in a sauce pan and bring it to a boil. Boil the mixture for 5 mins.
Now take it off the heat and add in chopped chocolate. Let it sit for 5 mins.
Whisk till chocolate melts.
Set aside in fridge for 30 mins to firm.
Remove it and whisk till creamy. Frosting is done.
Now take cooled cake, spread frosting all over it and sandwich with the other cake. Spread frosting all over the cake and let it set in fridge for 30 mins.