• Preheat oven to 425°F/220°C.
• Whisk the flour, xanthan, baking powder, salt and sugar together.
• With a pastry blender, add the butter into the flour mix until crumbly.
• Stir in milk. Before you completely combine the dough together, add the zest and cranberries. Mix until flour is completely combined.
• Gently pat dough into a circle (approximately 8–inch/20-cm diameter).
• Slice the scones into 6 pieces and place on a greased baking sheet. I didn't catch this step for some reason and I actually just partially cut though the round for 6 scones and ended up cutting them all the way through after baking. It worked fine.
• Coat a thin layer of the “egg” wash by whisking the water and cornstarch together, and then brushing onto the dough with a brush.
• Bake 15 to 20 minutes or until light brown.
• Allow cooling on a baking rack for 10 minutes.
• Coat the tops of the scones with the sugar glaze.

To make the Glaze

• Combine all ingredients to make a paste thick enough to stir but not too runny.