Preheat your oven to 200℃ fan/ 220℃. Line a baking tray with greaseproof paper and place in the oven to heat up.
Make sure you have your buttermilk. If you don't have any see note 3.
Mix your gluten free flour, xantham gum, baking powder and chopped butter in a mixing bowl.
Rub together the butter and dry ingredients using your fingers until it forms a crumble like mixture.
Stir in most of your grated cheese, add salt and pepper, mustard powder and chopped chives.
Make a well in the middle, pour in your buttermilk and work the dry ingredients into the buttermilk using a large metal spoon until combined. This may take a while but keep going it should eventually come together.
Flour the work surface, remove the dough from the bowl and kneed it slightly until it all comes together nicely. Do not over kneed.
Place a large piece of greaseproof paper on the work surface, place the dough onto it and flour your rolling pin.
Slightly roll the top of the dough so it's flat. Push together the sides until it is 4cm thick. (For gluten free scones like this you want the dough to be almost the height you'd like them).
Using a 4.5-5cm cutter, push down so you make 8 scones. Pull off the excess dough and re-roll if necessary.
Take out the baking tray in the oven, place your scones onto it and using a pastry brush, egg wash the top and sides of the scones. I put plenty on so they get a good colour.
Sprinkle the rest of the cheese on top of them including the optional parmesan if using.
Place in the oven for 12-15 minutes. Remove the scones from the oven and if they're golden on top and on the bottom they are baked.
Leave to cool on the tray or slather on some butter whilst warm! Enjoy!