75ml/2陆fl oz elderflower cordial (one that has a 1 to 10 dilution ratio)
1 lime, zest only, finely grated
100ml/3陆fl oz freshly squeezed lime juice (about 3 limes)
mint sprigs, for garnish
1 x 400g/14oz tin condensed milk
50g/2oz caster sugar
icing sugar, to taste
175g/6oz digestive biscuits (or ginger biscuits)
80g/3oz butter, melted
200ml/7fl oz double cream
3 free-range egg yolks