Throw all of the ingredients into the food processor and blitz until you form a nice firm dough. The mix can be a little bit fluffy, but if you grab a handful of it and if it sticks together, then you've got the right consistency.
Roll the mix between two pieces of non-stick parchment that has been cut to the size of your baking tray, until it's about three millimetres thick. Try and keep it as even as possible to ensure an even bake. Peel off the top layer of parchment and transfer the bottom layer of parchment to the baking tray.
Score along the mix with a blunt knife to create even squares. You don't need to separate the squares as they will crack really easily once they have been cooked.
Bake in the oven for about 15 minutes at 180 degrees. Keep an eye on them though, as they can burn quite easily. As soon as the biscuits are a nice golden brown, they are ready to come out to the oven.
Allow to cool and then simply snap each individual cracker away. These can be stored in an air-tight container for a couple of days, or they can be frozen and defrosted. Just put them back in the oven for 5 minutes or so to crisp them up.