Blitz flour, icing sugar, and salt in a food processor. Add butter and pulse until it looks like fine breadcrumbs.

Add yolk and iced water, one tablespoon at a time, until it just comes together.

Shape into a disc, wrap, and chill 30 minutes.

Lightly grease and flour a 24 cm pie dish.

Roll pastry out between two sheets of baking paper to ~3 mm thick, then use the paper to help lift it into the dish.

Press gently to fit, trim edges neatly, then use the back of a fork to make little indents around the edge of the pastry base for a classic bakery finish.

Chill in freezer 15 minutes.

Heat oven to 190°C (fan 170°C). Line pastry with baking paper and fill with baking beads/rice. Bake 20 minutes.

Remove paper and beads, bake another 8–10 minutes until lightly golden. Cool slightly.

In a saucepan, whisk custard powder, sugar, and a splash of the milk until smooth.

Add remaining milk gradually, whisking to avoid lumps.

Cook over medium heat, stirring constantly, until the custard thickens.

Remove from heat and stir through vanilla.

Reduce oven to 170°C (fan 150°C).

Pour custard into the pastry shell, smooth the top, and grate nutmeg evenly over.

Bake 50–55 minutes, until the custard is set around the edges with a gentle wobble in the centre.

Cool completely before slicing.