Grease and line a 23cm spring-form cake tin with melted butter and greaseproof paper.
Crush the gingernut biscuits in a food processor until they achieve a fine breadcrumb texture.
Mix biscuit crumbs with melted butter and press firmly into the base of the tin before chilling.
Soak gelatine leaves in cold water for 10 minutes until soft.
Fold mascarpone, lemon zest, whipped cream, and caster sugar together in a bowl.
Dissolve the softened gelatine in warm lemon juice and 30ml of water over a low heat.
Combine the gelatine mixture into the mascarpone cream and marble through the lemon curd.
Pour the filling over the base, smooth the top, and chill in the fridge overnight.
Remove from the tin, garnish with berries, mint, and icing sugar, then serve.