Crush gingernuts in food processor, (or place in plastic bag and crush with rolling pin)
Mix the crushed biscuits with melted butter.
Press into the bottom of an 8 inch loose-bottom flan tin and place in fridge to set.
Beat mascarpone cheese, icing sugar to combine.
Mix in the lime and lemon zest and juice.
Spread evenly over the cooled base and chill for at least 30 mins.
6 servings