Line a 9x13-inch (23x33 cm) baking tin with parchment, leaving an overhang for easy lifting.

Cream the butter and sugar: In a large bowl, beat 1 cup (225 g) unsalted butter with 1/2 cup (100 g) caster sugar until pale and fluffy, about 2–3 minutes. This builds lightness without making the dough sticky.

Add flavor: Mix in 1 teaspoon vanilla extract and 1/2 teaspoon fine sea salt. If you’re using salted butter, reduce the added salt to a pinch.

Combine dry ingredients: In a separate bowl, whisk 2 cups (240 g) plain flour with 1/4 cup (30 g) cornflour.

The cornflour helps create that classic short, crumbly texture.

Make the dough: Add the dry ingredients to the butter mixture. Mix on low just until it comes together into a soft dough. Don’t overwork it or the shortbread will be tough.

Press into the pan: Tip the dough into the lined tin.

Use your hands or the bottom of a measuring cup to press it into an even layer. Aim for consistent thickness so it bakes uniformly.

Dock and chill briefly: Prick the dough all over with a fork. Chill the pan for 10–15 minutes to help prevent excessive puffing and spreading.

Bake: Bake for 28–35 minutes, until the edges are lightly golden and the top looks set and matte.

It shouldn’t brown deeply.

Score while warm: Remove from the oven and immediately slice into bars or squares using a sharp knife. Cutting while warm gives neat edges that won’t crumble.

Finish: Sprinkle the top with 1–2 tablespoons of sugar for a delicate crunch. Let cool fully in the pan, then lift out and separate the pieces.