Whisk the butter with the sugar until creamy. Add the salt and orange zest and finally the eggs.
In a separate bowl mix the flour, baking powder and cocoa powder. Then alternating mix one spoon of the flour mix and gulps of the Guinness with the dough.
I also added 100g chopped dark chocolate. Put the dough in a baking tin and bake for 50-55 minutes at 180C.
The ingredients for the frosting need mixing together thoroughly and then can be spread on the cooled down cake.
Chocolatey with a hint of Guinness. Delicious!