Add the gluten-free flour blend, xanthan gum (if using), instant yeast, sugar, and salt to the bowl of a stand mixer. Briefly whisk or stir to combine.
In a small bowl, measure the egg, warm water (105–110°F), melted coconut oil, and apple cider vinegar.
Whisk the wet ingredients until fully combined and smooth.
With the paddle attachment in place (or a rubber spatula) turn the mixer to low speed and slowly add the wet ingredients to the dry ingredients. Scrape down the bowl once, then increase to medium speed and mix for 3 minutes.
Spray a 9-inch round cake pan evenly with cooking spray.
Using a 1/4-cup measuring cup or large scoop, portion 9 mounds of dough into the pan, one in the center and 8 around it. If desired, lightly wet a rubber spatula and gently smooth the tops of the rolls.
Cover the pan with a clean towel or plastic wrap and let the rolls rise in a warm place for 25–35 minutes, or until about 50% larger in volume.
Preheat the oven to 400°F. Bake the rolls for 26–28 minutes, or until golden brown. If the tops brown too quickly, loosely cover with foil near the end of baking.For best results, the internal temperature should register about 210°F on an instant-read thermometer. Cool slightly, then serve warm.
Notes
Don't double the recipe - make 2 batches side by side instead
Let the rolls rise only until 50% larger in size
The batter will look like thick cake batter - and that's ok!