Chocca Mocca Cake

This is a long-standing favourite of mine, but I have no idea where I originally found this recipe! The version pictured is my birthday-cake version, which is just decorated with icing sugar made up with cocoa powder and water to give it a chocolate flavour, and chocolate buttons.
Cream 175g butter and 175g brown sugar (unrefined if poss; I used molasses here as it gives such a lovely dark colour and rich flavour).
Beat in 2 eggs, 2 tbsp golden syrup, and 4 tbsp milk.
Make a paste in a mug of 2 tsp coffee and 2 tbsp cocoa with just enough hot water to mix it thoroughly (between 2-4 tbsp). Add this to the bowl and mix in.
Fold in 200g self raising flour.
Bake at 160 degrees for around an hour. I like a round tin for this one.
Use the clean skewer test to see when it's done, and put foil on top if it starts crusting and burning.