In a bowl, rub together the flour and butter until it resembles fine breadcrumbs. Stir in the icing sugar. Add enough water to mix into a firm dough. Roll out and use to line a 24cm loose-based tart tin. Chill in the fridge for 20 minutes.
Preheat the oven to 200°C/fan 180°C/gas mark 6. Line the tart case with baking parchment, then fill with baking beans or uncooked rice and bake for 10 minutes. Remove the baking beans and bake for a further 5 minutes, until firm.
Meanwhile, whisk the eggs with the sugar in a bowl until combined. Add the golden syrup, salt and melted butter. Sieve in the extra 2 tbsp flour and stir to combine. Add the chopped pecans and pour the mixture into the pastry case. Arrange the whole pecans on top.
Bake for 10 minutes, then reduce the heat to 160°C/fan 140°C/gas mark 3 and bake for 30-40 minutes, until the centre no longer feels wobbly. Gently heat the extra 1 tbsp golden syrup and brush over the top of the pie to glaze. Leave to cool before slicing.