Make the pastry: In a large bowl, rub the cold butter cubes into the flour, icing sugar, and salt using your fingertips until the mixture looks like coarse, pale breadcrumbs. You should still see small, pea-sized pieces of butter — that's what creates a flaky texture. Add the egg yolk and two tablespoons of ice water, then gently bring the dough together with your hands. If it feels dry, add more water a teaspoon at a time. The dough should just hold together when squeezed. Wrap it in cling film and flatten into a disc. Chill for at least one hour — this relaxes the gluten and prevents shrinking.

Toast the pecans: While the pastry chills, preheat your oven to 180°C (160°C fan) and spread the pecan halves on a baking tray. Toast for 6–8 minutes, shaking the tray halfway through. You'll know they're done when the kitchen smells wonderfully nutty and the pecans have darkened a shade or two. Let them cool completely — this deepens their flavour and keeps them crunchy in the pie.

Blind bake the pastry case: On a lightly floured surface, roll the chilled dough out to a circle about 30cm in diameter and 3mm thick. Gently lift it into a 23cm loose-bottomed tart tin, pressing it into the edges and leaving a little overhang. Prick the base all over with a fork. Line with parchment paper, fill with baking beans or rice, and bake at 180°C (160°C fan) for 15 minutes. The edges should look dry and just starting to colour. Remove the parchment and beans, then bake for another 5 minutes until the base is pale gold and looks set. Trim the overhang with a sharp knife while it's still warm.

Whisk the filling: In a large mixing bowl, whisk the eggs until they're foamy and pale yellow — about 30 seconds of brisk whisking. Add the dark brown sugar and whisk until it's dissolved and the mixture looks thick and glossy. Pour in the golden syrup, melted butter, vanilla extract, and salt. Whisk until everything is smooth and fully combined. The mixture will smell deeply of butter and caramel. Finally, sprinkle over the tablespoon of flour and whisk until there are no lumps — this helps the set.

Assemble the pie: Arrange the cooled, toasted pecans in a single layer over the bottom of the blind-baked pastry case. Don't pile them up — a single layer ensures every bite has a nut. Slowly pour the filling over the pecans, making sure it seeps down between them. The pecans will rise to the surface as it bakes, creating that classic, beautiful top.

Bake to perfection: Place the pie on a baking tray and bake at 170°C (150°C fan) for 45–50 minutes. After 30 minutes, if the edges are browning too quickly, tent the pie loosely with foil. You'll know it's done when the filling is set around the edges but still has a slight, gentle wobble in the very centre, like a firm jelly. The surface should be a deep, burnished gold. A skewer inserted an inch from the edge should come out clean, but the centre will still be soft — that's your cue.

Cool completely: This is the hardest step. Let the pie cool on a wire rack for at least 3 hours, or ideally overnight. The filling needs this time to fully set into a sliceable, fudgy texture. If you cut it warm, it will run everywhere. You'll see the surface slowly settle and become smooth and glossy as it cools.