Preheat the oven to 170C / 150C Fan / Gas 3.

Butter an 18cm/7 inch shallow cake tin.

Stir together in a bowl the flour, salt and sugar.

Rub in the butter then squeeze the mixture together into a rough ball of dough.

Press the dough into the base of the cake tin, making sure you go right to the edges, smoothing the top with a spoon.

With a sharp knife, mark the top into 6 or 8 triangles.

Sprinkle with a little sugar then bake until set and golden (30-40 min).

Cut deeply into the marks you made earlier & leave to cool in the tin before turning out.

Store in an airtight container and eat within 2-3 days