In a large mixing bowl, combine flour, butter, sugar, salt, baking powder, lemon zest, and lemon essence. Use your fingers or a pastry cutter to mix until the mixture resembles coarse crumbs.
Add the eggs to the mixture and knead gently until it forms a firm dough. Wrap it in plastic wrap and let it chill in the fridge for thirty minutes.
Preheat your oven to 170°C (340°F) while you roll out the chilled dough on a lightly floured surface.
Transfer your rolled dough onto a baking sheet dusted with flour.
In a separate bowl, mix the berries with sugar and starch. Toss gently to coat the berries.
Spoon the berry mixture into the center of the dough, leaving a five-centimeter (two inches) border around the edge.
Carefully fold the edges of the dough over the filling, pinching them together to create a rustic crust.
Bake in the preheated oven for 45 minutes, or until the crust is golden brown and the filling is bubbling.
Remove from the oven and let cool slightly. Serve warm with ice cream or a dusting of powdered sugar and fresh mint.
