• Mix the tapioca starch and 1 to 1 flour in a small bowl. In another bowl, add ½ cup of mixed flours together with the yeast, milk, and melted butter. Stir and let sit for 15 -20 minutes.
• Stir the yeast mixture into the sourdough mixture. Add in remaining flour, salt, and sugar to the bowl and stir by hand to combine completely. Cover with a towel and let rise in a warm place for 1 ½ - 2 hours until puffy and risen to 1 ½ times the size..
• On a well floured (with gluten free 1 to 1 flour) board, stir into the dough ½ -¾ cup Bob’s Red Mill Gluten Free 1 to 1 Baking Flour, to make a pliable, but not too soft or sticky dough. 
• Prepare a 12” cast iron or a 9 x 13” glass or ceramic casserole, greasing with olive oil or canola spray. Roll out or press with your hands to a 13” x 10” rectangle.

Filling

• In a small bowl combine the sugars and the cinnamon. 
• Brush half of the melted butter on the rectangle of dough.
• Sprinkle the cinnamon sugar filling over the top of the dough rectangle leaving ½ “ around the sides uncovered. Pour the rest of the melted butter evenly over the top.
  
• Roll up from the long side of the rectangle. Cut the roll in half with a sharp knife, then each section into 5 equal pieces. Transfer each as you cut into the prepared pan. Cover with a towel and let rise for half an hour.
  
• Preheat the oven to 375 degrees. Bake for 25-35 minutes. Remove from the oven when golden brown on top.
  
• Combine the glaze ingredients together and stir until smooth.
  
• Drizzle the glaze below over the tops of the cinnamon rolls and serve yourself one! Best enjoyed while warm but can be reheated in a 325 degree F oven for 5-8 minutes.