Heat oven to 190C/fan 170C/gas 5. Butter two 20cm sandwich tins and line with non-stick baking paper. In a large bowl, beat all the cake ingredients together until you have a smooth, soft batter.
Divide the mixture between the tins, smooth the surface with a spatula or the back of a spoon, then bake for about 20 mins until golden and the cake springs back when pressed. Turn onto a cooling rack and leave to cool completely.
For the fudge frosting, heat the cream until it just begins to boil. Take off the heat and add butter, honey and chocolate (broken into pieces).
Leave to melt for 5 mins, then stir briefly to combine - don't over-mix or it will lose its shine. Sandwich the cakes with a third of the just-warm frosting and spread the rest over the top and sides. Top with shaved or grated chocolate, if you like.