Preheat the oven to 180°C using top and bottom heat (no fan).
In a bowl, combine the ingredients for the dough(soft butter, sugar, baking powder, oil, and flour). Mix until a smooth dough forms.
Place the dough in the fridge while you prepare the filling (about 10–15 minutes).
In a separate bowl, combine all the filling ingredients and mix until well blended.
Grease about 14 mini tart molds. Press the dough evenly into each mold, covering the base and sides and leaving enough space for the filling.
Spoon the filling into each tart shell.
Bake in the center of the oven for 15 minutes, or until lightly golden.
Allow to cool slightly, then dust with icing sugar before serving.