Place butter chunks and milk into a microwave safe bowl and heat for 1 minute. Check and stir. Microwave another 30 seconds until butter is almost completely melted. Remove and set aside.
In large mixing bowl, add flour, xanthan gum, yeast and salt. Stir to combine.
Add warm milk mixture, maple syrup, vanilla extract and egg. Whisk until no lumps remain.
Cover bowl loosely with plastic wrap and let rise in a warm place for 1 hour. Give it a gentle stir.
Preheat waffle iron. Spray with cooking spray.
Pour ¾ cup of the waffle batter onto hot waffle iron. Let cook until desired shade of golden brown is reached (usually about 4 minutes each).
Remove and serve with fruit and/or syrup.
Video
Notes
Make sure all ingredients are at room temperature.
The batter can be prepared ahead of time - just mix it and let it sit on the counter for 1 hour, then refrigerate the batter for up to 24 hours. Use immediately after removing from the refrigerator.
Waffles can be made and then placed on a rack in a 200 F oven to keep warm.