1. Turn the oven to 175°C (345°F).
2. Whisk the eggs, sugar and vanilla until white and really fluffy.
3. Melt the butter, add the sour cream and mix this into the eggs.
4. Mix the flour, baking powder, cocoa and salt and carefully fold into the other ingredients.
5. Coarsely chop the chocolate and melt it in a water bath (in a bowl over boiling water). Add it to the batter.
6. Pipe or spoon out the mixture onto baking paper with a tablespoon.
7. Bake them in batches in the middle of the oven for about 10 minutes.
For the frosting
1. Mix the butter, icing sugar, vanilla, cocoa and cream cheese until creamy. Add the coffee and whip until fluffy with an electric mixer.
2. Pipe the frosting onto the underside of one cake and put it together with another cake (without frosting), like a macaron. Pipe some frosting on top and garnish with a sugar rose and some sprinkles.
Hello Cupcake! by Leila Lindholm
Hello Cupcake! is a glorious little book about cupcakes and whoopie pies from Leila Lindholm - Sweden's answer to Nigella Lawson. Discover recipes for wedding cupcakes, After-Eight cupcakes, Miss Piggy cupcakes, lemon meringue whoopie pies and banoffee whoopie pies. Published by New Holland Publishers, priced £12.99.