Line a 20cm springform cake tin with baking parchment. Combine the digestives and butter in a bowl and mix well. Press into the base of the prepared cake tin.
In a saucepan over a medium heat, combine the caster sugar and raspberries along with the water and lemon juice. Cook for 20 minutes over a low to medium heat until the raspberries are soft. Transfer to a food processor and blend until smooth. Press through a sieve into a clean saucepan. Soak the gelatine leaves in cold water for 5 to 6 minutes. Squeeze out any excess liquid then add to the raspberry purée and warm over a low heat until dissolved.
In a large mixing bowl, whisk the double cream until light and fluffy, then mix in the yoghurt and cream cheese. Gradually add the raspberry purée mixture and whisk until light and airy. Spoon into the prepared cake tin and smooth over the biscuit base. Gently smooth the top of the cheesecake. Chill in the fridge for 6 hours or overnight.
For the topping:
Remove the cheesecake from the fridge and carefully pop out of the cake tin and onto a serving plate. Arrange the raspberries on top of the cheesecake in a circle, pointing outwards. Serve.