1Dry out the filo pastry by leaving the sheets uncovered in a warm dry place, ideally the day before.
2Add all syrup ingredients (sugar, water, orange juice, orange zest, and cinnamon stick) to a pan over high heat and stir until the sugar has melted and the syrup begins to boil, then remove from the heat and leave to cool.
3Whisk the Greek yoghurt and orange juice in a mixing bowl until well incorporated.
4Add the sunflower oil, sugar, vanilla extract, eggs, orange zest, baking powder, and salt to the bowl and whisk well until combined.
5Add the dried filo pastry to the cake mix gradually, stirring continuously until fully incorporated.
6Pour the mixture into a greased baking tray and bake at 170°C.
7Check doneness by inserting a knife into the centre of the cake; it is ready if it comes out clean.
8Remove the cake from the oven and immediately pour the cooled syrup over it.
9Leave to cool and let the syrup soak in for a couple of hours, ideally until the following day.