Grease a 9″ spring bottom pan and line the bottom with parchment paper. Pre heat the oven to 180 C.
Melt the chocolate and butter in a large bowl placed over a pan of simmering water. Once its all melted, add the coffee and keep it aside.
In another bowl, beat the eggs, sugar and vanilla until light and doubled in volume. Stir the chocolate mixture into egg mixture. Pour into the prepared pan. Bake for about 40 – 50 minutes. It will get puffed up and then fall once it cools. Do let cool completely and turn out from the pan. I let the cake cool in the pan and then refrigerated it for a couple of hours before releasing it.
Note : You will not be able to test this cake with a tooth pick as it is meant to be gooey in the center.