Preheat the oven to 180°C and grease and line a 20cm springform cake tin.
Crush the digestive biscuits into fine crumbs using a food processor or rolling pin.
Mix the crumbs with melted butter and press into the base of the tin.
Bake the biscuit base in the oven for 5 minutes.
Beat the cream cheese, flour, caster sugar, vanilla, eggs, egg yolk, and one pot of soured cream until fluffy.
Fold in the raisins and rum, pour onto the base, and bake for 30 minutes.
Mix the remaining soured cream with icing sugar and spread over the cheesecake.
Bake for 10 minutes more until the filling is set but still slightly wobbly.
Cool the cheesecake then refrigerate until chilled before serving.