Preheat your oven to a hot 225 degrees Celsius and line a tray with baking paper.
In a large bowl, place the softened butter and sugar. Using hand held beater, beat on high speed for a moment or two, add in 1 Tablespoon of hot water, then beat again until it forms a very pale creamy mix.
Add in the egg and egg white and beat again thoroughly. Be sure to save that extra egg yolk as we'll use it to brush the tops of the scones.
Add in the mashed pumpkin and beat again to incorporate.
Place the flours and xanthan into the bowl and mix together by hand with a spoon. (If the mixture still looks a little wet add a little more self raising flour until a firm but workable dough comes together.)
Flour your bench top lightly with extra SR flour and turn the pumpkin dough mix out. Roughly knead the dough until it becomes smooth, then roll it out until it's a good 1 inch thick (approx 2.5cm).
Using a floured scone cutter (approx 6cm across), cut out shapes until all the dough is used. Continue to pull the off-cuts of dough together, re-roll and continue cutting until all remaining dough is used.
Transfer the scones to your prepared tray and place them so that they're just touching against each other. Brush with the remaining beaten egg yolk and place straight into a hot oven.
Bake for 10-15 minutes or until the scones puff up beautifully and the tops turn golden brown. Remove from the oven, transfer to a plate and serve with lashings of salted butter and a hot cuppa!