3 limes, zested (save the juice to use in the glaze)
300ml double cream
4 gelatine leaves
100g caster sugar
6 limes, juiced and pared, and zest of 3
Whizz the biscuits to crumbs in a food processor, or tip into a food bag and crush with a rolling pin. Mix with the melted butter, then press into the base of a 20cm springform cake tin. Chill in the fridge until needed.
Put the cream cheese, icing sugar and lime zest in a bowl, then beat with an electric mixer until smooth. Tip in the double cream and continue beating until completely combined. Spoon the cream mixture onto the biscuit base, working from the edges inwards and making sure that there are no air bubbles. Smooth the top of the cheesecake down with the back of a dessert spoon. Leave to set in the fridge while you make the glaze.
Soak the gelatine leaves in cold water. Tip the other ingredients for the glaze into a saucepan with 200ml water. Cook gently until the sugar has dissolved and the syrup is simmering. Drain and squeeze the gelatine of any excess water, then stir into the hot syrup to dissolve. Leave everything to infuse until just warm, then sieve the syrup into a jug. When cooled, pour over the cheesecake and put in the fridge overnight to set. Carefully remove the cake from tin before serving.