First, make the pastry. In a large bowl, use your fingertips to incorporate the cold butter into the dry ingredients to give a crumbly consistency. Slowly add the water into the bowl & mix until you have a smooth dough. Roll into a ball & wrap in cling film – refrigerate for 1-2 hours.
Preheat the oven to 180C & line a baking tray with parchment paper. Sprinkle the pecans across the tray in a single layer & bake in the oven for about 10 minutes, or until lightly toasted & fragrant.
In the meantime, in a large saucepan heat the sugar syrup, brown sugar, butter, and the vanilla over a low heat until the sugar has dissolved. Once dissolved, bring the mixture to the boil, then remove entirely from the heat & pour in the cream. Stir & allow to cool. Add the eggs into the saucepan one at a time, ensuring that each egg is fully incorporated before adding the next.
When the pecans are toasted, remove from the oven & allow to cool for a few minutes, then use your hands to coarsely break them up; set aside. Remove the pie dough from the fridge; butter & flour a 10-inch pie dish.
Using a rolling pin & a lightly floured surface, roll the dough out to make a large circle that can hang over the edge of your dish by roughly 2-cm. Place the dough into your dish & press down lightly; leave to rest in the fridge for 1-hour.
Preheat the oven to 180C again. Prick the base of the pastry with a fork, cover with parchment paper and cooking beans & bake for 15-minutes. After 15-minutes, remove the paper & the beans & bake for a further 5-minutes until dry & lightly golden.
Spread the pecans over the base & pour the filling mixture over the top. Place in the preheated oven & bake for about 40 minutes, or until the top is glimmering but the centre is still slightly wobbly.
Remove from the oven & brush lightly with the sugar syrup. Leave to cool before cutting.