Preheat oven to 180*C. Brush a shallow 28x18 oblong cake tin (I used a round one) with butter and line with grease paper.
Place butter and chocolate in a metal mixing bowl and melt over a pan with boiling water. Stir until combined and remove from heat.
Add flour, sugar, eggs & milk to mixture- if you have a processor, use the pulse action for 20 seconds, if not- I just whisked until smooth. Use a metal spoon to fold in walnuts.
Spoon mixture into prepared tin, smooth the surface and bake for 55 minutes or until it passes the skewer test. Leave cake in tin for 5 minutes before turning onto wire rack to cool.
While cake is in the oven you can prepare your Rich Chocolate Icing.
Method (icing):
Place chocolate, butter & essence in metal mixing bowl and melt over a pan with boiling water. Add icing sugar and mix with hand mixer or egg whisk until smooth. Allow to cool- mixture will harden and if you time it right, should be perfect to spread onto cake when cake has cooled. Sprinkle some chopped walnuts and choc chips over the top and enjoy with a nice hot cuppa!