Preheat the oven to 180’C and grease and line 2 x 8” cake tins
Beat together the butter and sugar until light and fluffy.
Beat the eggs into the mix one at a time.
Add the sour cream and stir until well combined.
Sift in the flour, baking soda, bicarb, cocoa powder and orange zest.
Divide the mixture between the two tins and bake for 30-35 minutes, test by checking that the sides have come away slightly from the tin and if you lightly press the top of the cake it should spring back up.
Leave the cake in the tins to cool slightly before removing and leaving to cool completely on a wire rack.
To make the frosting, add a little water to the cocoa to make a paste and stir into the melted chocolate.
Beat the cream into the mixture until well combined.
Spread half the frosting on one of the cake layers and place the other layer on top.
Using a pallet knife, spread the remaining icing neatly on the top.
Enjoy with fresh berries and cream or simply with a comforting cup of afternoon tea.