01 - Combine crushed graham crackers or digestive biscuits with melted butter in a bowl. Mix until crumbs are thoroughly moistened. Divide evenly among six serving glasses or ramekins, pressing gently to create a smooth, compact layer.
02 - In a mixing bowl, beat softened cream cheese until smooth. Add powdered sugar, vanilla extract, and lemon zest if desired, mixing until fully incorporated. In a separate bowl, whip cold heavy cream to stiff peaks, then gently fold whipped cream into the cream cheese mixture until homogeneous. Spoon or pipe the filling over the prepared biscuit base in each glass.
03 - In a small bowl, toss mixed berries with sugar and lemon juice. Allow the mixture to macerate for 10 to 15 minutes until berries release their juices.
04 - Layer the berry mixture on top of the cheesecake filling in each glass.
05 - Refrigerate assembled desserts for at least 3 hours, or overnight, until set. Serve cold.