270g plain flour
150g unsalted butter, cold and cubed
50g hazelnut meal
½ tsp salt
120g caster sugar
3 large egg yolks
1 vanilla bean, seeds scrapped
1 egg, for egg wash, whisked
Lemon Custard Filling
6 lemons, zest finely grated and juiced
300ml double cream
390g caster sugar
9 large eggs
1 large egg yolk
1. For the pastry. Using a food processor, Place flour, butter, hazelnut meal, salt, icing sugar, egg yolks and vanilla seeds in and pulse until it resembles wet sand. Remove from processor and press together into one mass. Wrap in cling film and rest in the fridge for 30 minutes
2. To roll out pastry flatten the dough a little with your palms. Then place in between two pieces of baking paper. With a rolling pin roll pastry out to 2 millimeters thickness. Then line a 28cm tart pan with the pastry. If it cracks and gaps form simply use some excess pastry to fill the gap in, just press it in nice and firm. Allow for a little over-hang as the pastry can shrink a bit when baking. Chill in freezer for another 30 minutes.
3. Pre heat oven to 190°C, remove chilled pastry from freezer and prick the base with a fork. Line with baking paper and weigh down with baking beads. Bake for approx. 20 minutes or until fully cooked.
4. Remove from oven and brush a layer of whisked egg onto the tart shell to seal. Return to blind bake for 10 minutes. Remove and allow to cool.
5. For the custard filling. Combine lemon zest, lemon juice, double cream, sugar, and eggs in a large bowl that fits over a saucepan of simmering water to create a bain-marie. Stir continuously and using your thermometer, test when the mixture reaches 60°C. Once it reaches 60°C strain it into a jug.
6. Reduce oven to 120°C and warm tart shell up again, once warmed gently slide oven tray out and pour in custard filling. Close oven and set a timer for 25 minutes.
7. Every 10 minutes test the centre of the custard with thermometer. Once the centre reaches 70°C, which should take about 25 minutes, remove from oven and allow to cool and set.
8. It’s ready to enjoy once it’s cooled to room temperature.