In medium-large bowl, dissolve the yeast in water and 1 tsp sugar. Let it puff up for 5 minutes.
1 tbsp instant yeast, ¾ cup warm water, 1 tsp sugar
Add the remaining 1 tbsp sugar, butter, salt and eggs and beat together.
1 tbsp sugar, 56 g butter, ¾ tsp salt, 3 large eggs
Add flour and xanthan gum and beat thoroughly until the batter is liquid and smooth.
170 g gluten free flour, ½ tsp xanthan gum
Grease a challah form and fill 3/4 with the batter. The batter will rise significantly and can overflow the form.
Let proof for 45 minutes.
Bake on 180C (fan) for 35 minutes. Then turn it out onto a baking tray, brush with egg white and bake for additional 15 minutes until golden brown.
1 egg white