To make your sponge:
Preheat the oven to 190˚C/375˚F/gas 5. You can make your cakes like this (by hand), or in a food processor. Beat the butter and sugar together with a wooden spoon, until very light and fluffy. Add the eggs one at a time, beating each one in well before you add the next. Sift in the flour. Finely grate in the zest of the lemon then fold the mixture together.
To bake your cakes:
Place 18 paper cake cases into muffin tins. Use tablespoons to evenly divide the mixture between the paper cases. Put the muffin tins into the oven and bake for 15 minutes. You can check to see if the cakes are cooked by sticking a cocktail stick right into one of them. Remove it after 5 seconds and if it comes out clean they’re cooked; if it’s slightly sticky they’ll need a bit longer, so put them back in the oven for another 5 minutes, or until cooked through and golden on top. If you cook them for too long, though, they will go dry so keep an eye on them. Remove the cakes from the tins and transfer to a wire rack to cool.
To make your icing and ice your cakes:
Mash up 50g of your chosen berries with a fork or whiz them in a food processor. If the fruit has pips you may want to pass it through a sieve to make it lovely and smooth. Sift over the icing sugar and mix until you have a smooth paste.
When the cakes have cooled completely, drizzle a teaspoon of your icing over each one then top with the rest of the fruit – if you’re using strawberries, slice them up first.