Mary Berry’s Zesty Lemon & Lime Cheesecake

1. Make the Biscuit Base
Crush biscuits into fine crumbs (use a food processor or rolling pin).
Mix with melted butter and sugar (if using).
Press firmly into a 20cm springform tin and chill for 30 mins.
2. Prepare the Filling
Beat cream cheese and icing sugar until smooth.
Add lemon & lime zest/juice and vanilla. Mix well.
In a separate bowl, whip double cream to soft peaks.
Gently fold cream into the cream cheese mixture.
3. Assemble & Chill