Chop butter with a knife, add sugar and work together with with fingers (wear latex gloves if you like) until the sugar is mixed into the butter.
Add the egg, yoghurt and vanilla essence then continue to mix until the mixture becomes smooth.
Add half the flour and baking baking powder and mix to combine.
Add the rest of the flour and bring the whole dough together into a ball with your hands.
Roll out 3/4 of the dough in between 2 sheets of baking paper to about 5mm (1/4 inch) thick.
Place pastry in the paper-lined tray and spread to the edges.
Prick the base of the pastry around with a fork, spread lemon curd evenly over the pastry and sprinkle with blueberries.
Dot the slice with chunks of leftover pastry.
Bake for 30-35 minutes, or until the pastry is nice and golden brown. Remove from oven and cool on a wire rack.