Preheat the oven to 180°C/160°C fan and grease and line two 20cm/8" round baking tins.
In a medium mixing bowl, whisk together the flour, baking soda, xanthan gum, cinnamon and ginger until well combined.
In a separate large bowl, whisk the oil with both sugars and the vanilla extract until smooth.
Add the eggs one at a time, whisking to combine after each addition.
Sieve your whisked dry ingredients into the bowl with the wet ingredients, and gently fold everything together until just combined.
Finally, add the grated carrot and raisins (if adding) and fold once more until mixed through.
Distribute the mixture evenly between your two tins and bake for 35-45 minutes, or until a skewer poked into the centre of the cake comes out clean.
Leave the cakes in their tins for approx 10 mins before transferring them onto a wire rack to cool completely.