Preheat the oven to 220C/fan 200C/gas 7. Prepare a baking sheet with baking paper.

Put the gluten-free flour, baking powder and xanthan gum in a bowl. Chop the butter into cubes and add to the flour. Rub it in with your fingers until it forms what looks like breadcrumbs. Stir in the sugar and sultanas, if using.

Add the lemon juice and vanilla extract to the milk. Allow to sit for about 5 minutes to make your own homemade buttermilk.

Place the baking sheet in the oven whilst you make the scones. It helps if the baking sheet is hot when you place the scones on top of it.

Pour in the homemade buttermilk and work it in using a metal spoon. Keep working until it forms a dough (it might be a little sticky).

Flour your work surface and your hands, using extra gluten-free flour. Tip the dough on to the work surface and fold it over a few times to bring the dough together. It’s really important not to overwork the dough, or you will get tough, flat scones. Bring the dough into a rounded shape about 4cm-4.5cm thick. The taller, the better.

Using a cutter (about 45mm to 55mm wide), push down into the dough to make rounds. Ease out of the cutter and put to one side until you have used up all the dough (keep re-rounding the dough, but remember not to overwork it). Brush the tops of the scones with beaten egg.

Place the scones onto the hot baking sheet and bake for 12-15 minutes, or until golden on top and golden on the base. Serve up warm with whatever you fancy, such as jam and clotted cream. You can warm them up later, eat them cold, or even freeze.