Combine softened butter and sugar in a mixing bowl and cream until light and fluffy about 3 minutes.
Add egg white, vanilla, orange juice and orange zest and beat until combined.
In a separate bowl combine flour, xanthan gum, baking powder and salt and whisk thoroughly to combine.
Add dry ingredients to the wet ingredients, beating on slow and scraping down the sides.
On a large ungreased baking sheet, place about a tablespoon of dough for each cookie, spreading into a 2x4 inch rectangle until all the batter is gone ( 36 small cookies) being sure to separate so they won't stick together when they spread.
Bake in a preheated oven for 10-12 minutes or until the cookies are set and edges are golden brown.
Allow to cool on the baking sheet for at least 5 minutes before removing with a spatula to a cooling
Melt chocolate in a double boiler, adding maple syrup, 1 tsp orange peel and 1 tsp orange juice. Working quickly (chocolate needs to remain warm whole piping), pipe about 1 1/2 teaspoons or filling onto 14 cookies.
Place other cookie on top (flat side in) to create a sandwich.