Method
Heat the oven to 180ºC / fan 160ºC / gas 4. Crush the digestive biscuits in a food processor (or put in a plastic bag and bash with a rolling pin). Mix with the melted butter. Press into individual springform tins and bake for 5 minutes, then cool.
Beat the cream cheese with the flour, caster sugar, a few drops of vanilla extract, the eggs and egg yolk and the pot of soured cream until light and fluffy. Stir half the raspberries, and divide between the tins. Bake for 20 minutes and then check, they should be set but slightly wobbly in the centre. Leave in the tins to cool.
Using the remaining raspberries, keep a few for the tops and put the rest in a pan with the icing sugar. Heat until juicy and then squash with a fork. Push through a sieve.
Serve the cheesecakes with the raspberry sauce and raspberries.