1. Preheat oven to 180°C (160°C fan) mark 4. For the cakes, grease and line 2 x 20.5cm (8in) round vake tins. Put the flour, bicarbonate of soda, cocoa, sugars and a pinch of salt into a large bowl or freestanding mixer. Into a jug, measure the soured cream, eggs and vanilla. Whisk briefly to combine. Pour on to the dry ingredients and whisk until fully incorporated, then whisk in the melted butter, coffee and Kahlúa. Divide the mixture equally between the tins.