Prepare the Orange Glaze first to allow for the glaze to cool. Melt unsalted butter in the microwave.
Mix 1/4 cup Xylitol into the hot butter. Return to the microwave for 45-60 seconds until Xylitol is melted.
Add remaining 1/4 cup of Xylitol to the butter mixture. Return to microwave for 45-60 seconds until Xylitol is melted. Be careful as mixture will be VERY hot.
Add vanilla extract and juice from 1 medium orange. Set aside until cooled, stirring occasionally. Prepare scones while waiting for glaze to cool.
Orange Zest Scones
Preheat oven to 400 degrees F. Line baking sheet with parchment paper.
In a large mixing bowl, combine gluten-free all-purpose flour, baking powder, baking soda, and salt. Set aside.
In a small bowl, combine granulated sugar and orange zest until sugar is moistened and zest is evenly distributed. Combine with flour mixture.
Grate frozen butter into mixture. Work the butter into the mixture until evenly distributed and mixture resembles coarse meal.
In a medium bowl, combine egg and sour cream. Stir until well blended and smooth. Add to flour mixture and stir until just combined. Do not over mix!
Dough will be sticky. Place dough between two sheets of parchment paper and roll dough to an 8" diameter. Using a pizza cutter or sharp knife, cut dough into 8 wedges. Separate and place on prepared baking sheet.
Bake for 15-17 minutes, or until light golden brown. Allow to cool for 10 minutes, then transfer to a cooling rack. Top with glaze.