Preheat the oven to 180˚C.
Melt the butter some a tablespoon of jam. Remove from the heat and set aside.
Lay a sheet of filo at the time on a work surface and brush with some jam and some of the melted flavoured butter. fold using the longest side into 5-6 to create bands of filo pastry.
Repeat until all the filo is used.
place in the tart shell starting from the centre to create a spiral. Adding more waved filo pastry until the whole tart shell is filled.
transfer the tart in the oven for 10-15 minutes to allow the filo to crisp up.
In the meantime, Prepare the custard mixture. In a bowl, combine the milk with the caster sugar, lemon zest and vanilla extract and eggs. Keep aside.
Once the filo is baked, remove from the oven and drop the oven temperature to 150˚C.
Pour the custard mixture over the filo.
Spoon extra jam if desired and place back in the oven at 150˚C for 25-30 minutes until the custard is just set.
Remove from the oven and set aside to cool for 30 minutes.i like to serve this dessert at room temperature within a few hours but it can be served the next day too!