The cake chapter in my new book goes into some detail about getting the crumb moist and delicate: don't overbake it, add a little syrup while it's warm, keep it covered once cool and, if you want it extra soft, add two teaspoons of vegetable glycerine for every 200g flour. Or just eat it fresh.
75g dark chocolate
75ml sunflower oil
75g sour cream
125g caster sugar
75g runny honey
2 tsp vanilla extract
3 medium eggs
25g cocoa powder
175g plain flour
2 tsp baking powder
For the quick cake syrup
25g icing sugar
2 tsp vanilla extract
For the sour cream frosting
300g dark chocolate
50g unsalted butter
50g runny honey
25ml bourbon or brandy
100g icing sugar
125g sour cream
Line the base of two round 18cm sponge cake tins with a disc of nonstick paper and heat the oven to 180C (160C fan-assisted)/350F/gas mark 4. Meanwhile, get on with the cake mix – melt the chocolate, then beat in the oil, cream, sugar, honey and vanilla. Beat in the eggs one at a time, then stir together the cocoa, flour and baking powder, and sift in. Divide the mixture between the tins and bake for around 25 minutes, until a skewer pulls out with just a few crumbs sticking to it.
While the cakes are warm, make the syrup by stirring the icing sugar and vanilla with 25ml boiling water. Prick the cake tops, spoon over the syrup and leave to cool in the tin, covered with paper or clingfilm.
For the frosting, melt the chocolate and butter, stir in the honey, bourbon and sifted icing sugar, leave until cool, then beat in the sour cream. When the mixture firms slightly, beat again, sandwich the cakes together with it and spread the rest over the top and sides.