Whisk the eggs and sugar in a bowl until pale and foamy. Sift in the flour, cocoa powder, salt and baking powder and whisk again. Pour in the cream and melted butter and whisk until just combined.
Spoon the batter into the paper cases so that they are two-thirds full.
To make the icing, put the butter into a bowl and beat until pale and fluffy. Sift in the icing sugar and cocoa powder and beat again until smooth. Finally, fold in the cream cheese – don’t overbeat the icing at this stage or it might become too soft.
Spoon the icing into a piping bag fitted with a 2D nozzle (see tip). Gently squeezing the bag and starting in the middle of each cake, pipe the icing in circles until the top is covered. To decorate, scatter with mini sprinkles.