To prepare the pastry, combine flour, sugar, butter and egg in a food processor. Mix and blend until a smooth dough is formed. Put into a plastic bag or wrap in cling film. Chill in the refrigerator for 2530 minutes.
When chilled, roll out pastry on a lightly floured tabletop. Cut out circles to fit tart moulds, then carefully line the greased moulds with the pastry. Press and trim the edges. Prick the base with a fork. Bake the cases blind in a preheated oven at 190°C for 56 minutes. Allow to cool.
To prepare the filling
Beat cream cheese, butter and sugar until light and smooth, then add the egg. Continue to cream until well blended. Mix in whipping cream until combined. Lightly stir in flour and mix until well incorporated.
Spoon the mixture onto the pre-baked tart shells. Add a little blueberry filling. Use a wooden satay skewer to swirl it to create a marble effect.
Bake the tarts at 200°C for about 1013 minutes. Remove from the oven to cool a while before serving.