Grease and line a 20cm square or round cake tin with baking paper, and heat the oven to 180C (160C fan)/350F/gas 4.

Combine the ginger beer and butter in a large, wide saucepan large enough for the whole cake to be mixed in, so about three-litre capacity.

Set it over a medium heat and stir gently until the butter melts.

Off the heat, sift in the cocoa powder and sugar, whisk to combine, then leave to cool for five minutes.

Meanwhile, whisk the soured cream, eggs and vanilla in a jug, then pour into the ginger beer mix and whisk gently.

Sift the flour, salt and bicarbonate of soda into the batter and whisk gently until smooth and combined.

Pour the batter into the lined tin and bake for about 55 minutes, until a skewer inserted into the centre comes out clean.

Remove, leave to cool for 10 minutes, then remove from the tin and transfer to a rack to cool completely.

Meanwhile, put the cream cheese in the bowl of an electric mixer fitted with the paddle attachment and beat on medium-low until smooth.

Turn down the speed to low, add the icing sugar and beat for about 30 seconds, until incorporated.

Add the cream and ginger beer, turn up the speed to medium and beat for one to two minutes, until thick and smooth.

Refrigerate until needed.

To serve, use a spatula to spread the icing thickly over the cake.

Scatter the flaked chocolate over the top, then serve.

The un-iced cake will keep for about two days, but, once iced, it’s best to eat on the same

day.