Preheat over to 160 degrees Celsius fan forced. Grease and line the base of a 17 cm cake pan.
Combine butter, ½ of the chocolate, water, cocoa powder, coffee powder and vanilla in a medium saucepan. Cook, whisking continuously over a low heat until smooth and well combined. Remove from heat and stand until mixture is lukewarm.
Use electric beaters to whisk sugar and eggs in a large mixing bowl until pale and creamy. Whisk in chocolate mixture until well combined. Add the flour and whisk until combined. Add the remaining half of the chocolate chopped and combine.
Pour the mixture into the prepared cake pan and bake in a preheated over 55 minutes or until a skewer inserted in the middle comes out clean.
Remove from over and cool in pan. Cover the pan with cling wrap and place in the fridge for 30 minutes. Once chilled, remove cake from pan and wish a long, serrated knife, cut horizontally into 3 even layers. Glad Wrap well and set aside until assembly.
Recipe by The Life of Clare at http://www.thelifeofclare.com.au/katherine-sabbath-inspired-birthday-layer-cake/