Whisk together the gluten free flour, xanthan gum, tapioca starch, salt, cream of tartar, and baking soda in a large mixing bowl until well combined.

In a separate bowl, combine the granulated sugar, instant yeast, and warm milk, letting it sit for about 5 minutes until frothy.

Add the egg, egg white, melted butter, apple cider vinegar, and nutmeg (if using) to the yeast mixture, stirring to combine.

Pour the wet ingredients into the dry ingredients and mix until a soft, slightly sticky dough forms. Add more milk if the dough is too dense.

Cover the dough with a clean kitchen towel and let it rise in a warm place for about 1 hour or until doubled in size.

Lightly flour a clean surface and roll out the dough to about 1/2 inch thick. Cut out donuts using a donut cutter or two round cutters.

Heat oil in a heavy-bottomed pan for frying, or preheat your air fryer as per manufacturer instructions.

Carefully fry or air fry the donuts until golden brown on both sides, around 2-3 minutes per side. Transfer to a cooling rack.

Combine confectioners’ sugar, Lyle’s Golden Syrup, and water in a bowl, whisking until smooth. Dip each cooled donut into the glaze.