Preheat your oven to 190°C/gas mark 5. Line two baking sheets with greaseproof paper. Combine all the dry ingredients, including one of the optional flavourings if you are using them, and stir well.
Mix the maple syrup and coconut oil with 350ml water in a measuring cup. Add to the dry ingredients and mix well, until everything is completely soaked and the mixture becomes very thick.
Divide between the two trays and even out a bit, then put another piece of greaseproof paper on top. Use a rolling pin to roll out the mixture until it is about ½cm thick. Take the top layer of greaseproof paper off and use the tip of a sharp knife to score the mixture into rectangles.
Bake the crackers for 20 minutes. Remove from the oven and flip the sheet over, then peel off the greaseproof to expose the underside of the crackers. Put back into the oven for another 20 minutes. They're ready when they're firm and golden round the edges. Allow to cool, then break along the lines where they have been scored.
To flavour your crackers add 1 heaped tsp fennel seeds and a pinch of dried chilli or 1 tbsp raisins, roughly chopped, and a pinch of cinnamon with the dry ingredients in step 1.