Preheat the oven to 180C or 365F. Line two baking trays with baking paper.
In a medium sized mixing bowl, whisk together all the dry ingredients. Add the egg and use a spoon to combine. Once it starts to look like chunky wet sand, get your hands in there to bring the dough together, adding a dash of water if there are some dry spots. Be careful not to add to much water or the crackers will be harder to roll out.
Place the ball of dough between two sheets of baking paper. Use a rolling pin or wine bottle to roll the dough out until it is very thin. The thinner the crackers are, the better they taste. You should get around 20-25 from each batch.
Use a circular cutter (I used a scone cutter) to cut out the crackers. The dough is very easy to work with and you can re-roll it as much as you like. It might start getting a little oily, but the end result will be the same.
Arrange the cut crackers on the baking tray. You don't need to leave space between them as they don't spread. Cook for 10-13 minutes or until they are lightly golden and fragrant. I prefer to cook one tray at a time (I have a tiny oven) but what you prefer is up to you.
Once cooked, allow the crackers to cool before storing them in an airtight container. They keep really well for at least a week.