Preheat the oven to its highest setting with a heavy baking tray or baking stone in it.
In a small bowl combine the milk with ½ tsp. sugar and yeast. Allow to sit in a warm place for 4–5 minutes.
Sift the flours, xanthan gum, salt, and baking powder into a medium bowl. Mix them together in a separate bowl, and add the remaining ½ tsp. sugar, oil, yogurt, egg. Mix until smooth.
Add the yeast mixture to the flour mixture.
Form the dough into 6 equal-sized balls. Roll out the balls into a tear shape that is ¼ inch thick (use rice flour, if necessary, to prevent sticking).
Place the rolled-out dough onto the baking surface. Bake for 3 minutes, or until the naan puffs up and turns light brown. You may need to cook it on both sides.