First, activate the yeast by combining the warm milk, warm water, sugar, and yeast. Cover the yeast mixture and allow it to sit for 10 minutes. The yeast is activated when bubbles have formed. If after 10 minutes there are no bubbles, discard the mixture and repeat.
In a separate bowl, combine the flour, xanthan gum, salt, and baking soda. Whisk the dry ingredients to ensure that all ingredients are well combined.
Next, add the egg, apple cider vinegar, sour cream, and yeast mixture. Using either a stand-alone mixer with the paddle attachment attached at low-medium speed or your hand, combine the ingredients. Then, add the butter one tablespoon at a time, integrating the butter into the dough after each addition.
Divide the dough into two equal parts, transfer each dough to a greased bowl and cover tightly with plastic wrap to prevent the dough from drying.
Dust the working area and rolling pin with gluten-free flour. Working with one dough at a time, roll the dough into a rectangle with a thickness of 5-6 mm ( ¼ inch). Then, brush one tablespoon of butter onto the dough and sprinkle the cinnamon-sugar filling.
Roll the dough tightly into a log, and cut it into 5-6 equal rolls.
Repeat steps 5-6.
Transfer the 10-12 cinnamon rolls to a greased casserole and cover tightly with plastic wrap. Then wrap the casserole with a damp kitchen towel and allow the cinnamon rolls to rise at room temperature for 60-90 minutes.
Preheat the oven to 180°C (356°F).
Bake, the gluten-free cinnamon rolls for 20-23 minutes or until a thermometer inserted at the rolls' center reads 87°C ( 190°F).