Preheat the oven to 220°C (430°F) (without fan).
Place a baking tray in the middle shelf of the oven to warm up while you are making the scones.
Place the flour, salt, sugar, baking powder and nutmeg into the bowl of an electric stand mixer.
Add the butter and briefly mix with the flat paddle attachment until the mixture resembles damp sand. Alternatively, you can do this by hand by simply rubbing the fats into the flour with your fingertips.
Add the pumpkin purée and beat it into the mixture briefly.
Slowly add the buttermilk and quickly mix everything together. You may not need all of the buttermilk - just add enough buttermilk until the mixture just comes together into a rough dough. Try not to overwork the dough as this may lead to tough scones later.
Place the dough onto a floured work surface and pat it into a rectangle or circle shape about 3 cm (1 inch) high.
Cut your scones with a round cutter. You could also use a teacup or small glass to shape your scones. Use a straight up-and-down movement to cut the scones. Try not to twist the cookie cutter as this might prevent the scones from rising nicely later.
Dip the cutter into some flour to prevent the dough from sticking to it.
You can make the scones as little or as big as you like, adjusting the baking time accordingly. I use a 6 cm (2.5 inch) cookie cutter to make medium-sized scones.
Lightly re-shape the dough as necessary, but try to handle the dough as little as possible.
Arrange the scones closely together on a baking tray.
Make an egg wash by lightly beating together the egg and milk.
Brush the scones with some egg-wash.
Bake the scones in the oven for about 15-20 minutes (depending on size), or until they are lovely and golden.
You may need to test a scone to make sure that it is fully cooked through in the centre. A digital thermometer inserted in the centre of a scone should read about 85°C (185°F).
These scones are best served hot or warm, but they are also lovely served at room temperature.
Serve the scones warm with a spread of butter.
To stop the scones from developing a hard crust as they cool, cover the warm scones with a clean tea towel. The steam trapped under the tea towel will help to keep the scones soft.