225g salted butter , softened, plus extra for the tins
225g golden caster sugar
4 large eggs
225g self-raising flour
2 limes , zest finely grated
50g natural yogurt
lime wedges, lime zest and mint leaves, to decorate
For the syrup
3 limes , juiced (90ml)
100g light brown soft sugar
small bunch mint , leaves picked and roughly chopped
120ml white rum
For the buttercream
150g unsalted butter , softened
400g icing sugar , sieved
2 limes , zested
50g cream cheese
STEP 1Heat the oven to 180C/160C fan/gas 4. Butter and line two loose-bottomed 20cm round cake tins.
STEP 2Put the butter and sugar in a large mixing bowl. Beat for 5 mins with an electric whisk until pale and fluffy. Whisk in the eggs one at a time, then fold through the flour, grated lime zest and yogurt. Divide the batter between the prepared tins and bake in the centre of the oven for 25-30 mins, or until a skewer inserted in the middle comes out clean. Leave in the tins for a min, then turn out onto wire racks.
STEP 3To make the syrup, put half the lime juice and all the sugar and mint leaves into a saucepan and bring to a simmer, adding 1 tbsp water if needed to dissolve the sugar. Gently bubble for 7-10 mins, or until syrupy. Remove from the heat and stir through the rum and remaining lime juice. Leave to infuse for 10 mins, then strain into a bowl.
STEP 4Prick the warm cakes all over with a cocktail stick and pour over the syrup. Leave to cool completely.
STEP 5To make the buttercream, put the butter, icing sugar and lime zest in a bowl and beat with an electric whisk for 5 mins until light and fluffy. Beat in the cream cheese until just combined, being careful not to overbeat.
STEP 6Put one of the syrup-soaked sponges on a large serving plate and spoon over one-third of the buttercream, spreading it over with a palette knife. Top with the other sponge and spread the remaining icing over the top and sides of the cake. Decorate with the lime wedges, lime zest and mint leaves. Will keep in the fridge for up to three days.