Put the flour, butter, salt, the Cheddar cheese and all but 1 tbsp of the Parmesan into a food processor.

Whizz together to form a dough: don't be tempted to add water as it's not needed.

Tip the dough onto a floured worktop, briefly knead until smooth then roll into a log shape approx 4cm in diameter.

Wrap in cling film and chill in the fridge for 30 minutes or until required.

You can also freeze at this point.

While the dough is chilling, preheat oven to 180C/160 Fan/Gas 4 and lightly grease a baking tray (you may need 2 trays).

When ready to bake, have ready a mug of hot water to dip your knife in now and then: this will make cutting the dough smoother.

Slice thin biscuits from the log and place them on the baking trays.

Brush with beaten egg, top with the reserved 1 tbsp Parmesan and any optional toppings such as smoked paprika or black pepper.

Bake for 10 minutes until the biscuits are golden.

Very carefully (they will be fragile) transfer the biscuits to a wire rack to firm up and cool slightly.

If not eating straight away, leave to cool completely before storing in airtight containers or freezing.