Separate out the egg whites into a measuring jug, then top up with warm water to 445 millilitres. Then in a large bowl, sift in the flour, Xanthan gum, salt, sugar and yeast and mix together with a spoon. Gradually add the egg/water mixture while mixing the ingredients of the bowl using a hang mixer with a dough attachment. Mix until all the egg/water is added and well mixed, roughly 2 to 3 minutes. Then cover with cling film and leave in a warm place (e.g. the radiator in your bathroom ensuring the door is closed) for 2 hours to rise.
When the time is up, lightly dust a work surface, your hands and the top of the dough with gluten free flour then pull the dough out of the bowl and onto the surface. Divide the dough into two then roll each one into a long sausage shape making sure to taper the ends. Place a sheet of baking parchment on a baking tray then lift the baguettes onto the tray. Score them with a sharp, wet knife (roughly just under 5 centimetres in), brush them with water and then cover in clingfilm and return to a warm place to rise for another 40 minutes while you preheat your oven to 230 degrees Celsius.
When the 40 minutes is over, place a baking tray with 125 millilitres of water on the bottom shelf then remove the cling film from the baguettes and add them to the middle shelf, close the door and bake for 30 – 35 minutes until they are a nice brown colour. Remove from the oven and leave to cool for 20 30 minutes before serving.