Caramelise the onions first, so they have time to cool down. They need to be cooled completely to room temperature before you add them to the scone dough.

Heat the olive oil in a pan over medium heat, then add the finely sliced onions, salt and pepper, and mix well.

Reduce the heat to medium-low and cook slowly, with occasional stirring, until the onions are soft and caramelised – they should be of a deep golden brown colour. That usually takes about 15-20 minutes.Tip: If the onions look dry or like they're starting to burn at any point, add a tablespoon or two of water and scrape up any browned bits stuck to the bottom and sides of the pan.

Transfer the caramelised onions to a bowl or plate and allow to cool completely to room temperature.

Adjust the oven rack to the lower-middle position, pre-heat the oven to 400ºF (200ºC) and line a large baking sheet with parchment/baking paper.

In a large bowl, whisk together the gluten free flour blend, baking powder, xanthan gum and salt.

Add the cold cubed butter and work it into the dry ingredients until you get a mixture resembling breadcrumbs, with a few pea-sized pieces here and there.

Add the grated cheddar cheese, chives and (cooled!) caramelised onions, and toss them in the dry ingredients until they're evenly distributed. If needed, you can rub the mixture between your fingertips to break apart any large pieces where the cheese or caramelised onions have stuck together.

Add the cold buttermilk and stir everything together until the dough starts clumping together. The dough will still be fairly shaggy at this point, but most of the flour should be hydrated (there shouldn't be any large patches of dry flour). If your dough seems too dry and doesn't want to stick together, you can add a tablespoon or two of extra buttermilk. Tip: The exact amount of buttermilk you’ll need can vary, depending on how thick/runny your buttermilk is and how much moisture your gluten free flour blend tends to absorb. The aim is to get a shaggy dough that holds together when you shape it into a disc (but it shouldn’t be too soft or sticky to the touch).

Turn out the dough onto a lightly floured surface and use your hands to press it together into a rough ball. Be careful not to overwork it, it needs to stay as cold as possible, otherwise the butter could start to melt. You don’t need to knead it – the aim is to press it together so it won’t fall apart when you cut it into the individual scones, but it doesn’t have to be perfectly smooth.

Press the dough into a roughly 7-inch (18cm) disc, about 1 inch (2.5 cm) thick.

Cut it into 8 wedges, either with a sharp knife or with a straight-edged metal pastry cutter (bench scraper).

Place the scones onto the lined baking sheet, spaced as far apart as possible, as they will puff up during baking.

Brush them with a bit of extra buttermilk and sprinkle with grated cheddar cheese.

Bake them at 400ºF (200ºC) for about 20 minutes or until they’re puffed up, golden brown and the melted cheese on top is nicely browned.

Cool the scones on the baking sheet for 10-15 minutes, then serve them warm.

The gluten free cheese scones are best served warm, on the day of baking.You can store them in a closed, air-tight container in a cool, dry place for up to 2 days. Because they contain so much cheese, they’ll seem quite hard and dry once they’ve cooled to room temperature – but you can easily return them to their original tender, soft texture by reheating them in the microwave (for 15-20 seconds) or in a 350ºF (180ºC) oven. Note that reheating them in the microwave won't crisp up the crust – but it will make their interior just as soft and tender as it was on the first day.