Preheat the oven to 360°F (180°C), if possible, without the fan. Spread 250 g flour out on a baking sheet in a thin and even layer.
2: Put in the oven for 10 minutes. Watch carefully - the flour should stay white, not take on any colour. Take out of the oven and leave to cool.
3:
Make the biscuit dough
Put into a food-mixer bowl: 100 g butter (cut into small pieces), 125 g caster sugar, 2 eggs, 2 pinches salt and the toasted flour when cooled (tip this straight into the bowl).
4: Mix until the dough is evenly mixed.
5: Tip the dough out onto a large sheet of plastic film, roll it into a large "sausage" and wrap in the film. Refrigerate the dough for 2 hours or overnight.
6:
Cooking
Preheat the oven to 360°F (180°C). Unwrap the roll of dough and slice into rounds about 1/4 inch (5 mm) thick.