Traditional Scottish Shortbread

Cream together softened butter and caster sugar until smooth.

Stir in plain flour (and a little cornstarch for extra crunch) until a firm dough forms.

Press the dough into a shallow baking tin or roll out and cut into 'fingers' or rounds.

Prick the surface with a fork in a decorative pattern.

Bake at 150°C for 30-35 minutes until firm to the touch but still pale golden (do not let it brown).

Sprinkle with a little extra sugar while still hot.

Cut into pieces while still warm, then let it cool completely to harden.