Instructions

1. First prepare a 8-inch baking pan or an 8x8 pan by lining it with parchment paper and buttering the paper with 1/2 tablespoon of the cinnamon sugar filling butter (Alternatively, skip the parchment paper and butter the pan directly - it's just more messy, but works great!).
2. Prepare the cinnamon sugar mixture. Combine the filling light brown sugar, cane sugar, and cinnamon, in a small bowl. Set aside
3. Warm the milk in a small pot to between 105-115°F (if you go over, let it cool until the temperature is within that range). Transfer to a wide mixing bowl and mix in 1 teaspoon sugar. Slowly sprinkle the yeast over the warm milk and use a spoon to mix completely. Let set aside for 10 minutes while the yeast activates and foams. If your yeast hasn't foamed up after 10 minutes, you may have bad yeast and you should try again with a new packet.
4. In a medium bowl, whisk together the tapioca starch, oat flour, sorghum flour, sweet rice flour, xanthan gum, baking powder, and salt. Set aside.
5. In the bowl of a stand mixer fitted with the paddle attachment, or a large mixing bowl with a hand mixer, combine 4½ tablespoons melted butter, remaining ¼ cup + 3 tablespoons sugar, and apple cider vinegar and mix until smooth. Add the egg and mix until completely incorporated. Add the milk yeast mixture and mix until completely incorporated.
6. With the mixer on low, slowly add the dry ingredients to the wet ingredients and mix until completely incorporated. Change to the dough hook and knead the dough on low for 1 minute. Let it rest for 1 minute. Knead again for one minute. Repeat 2x. The dough will be very sticky (more so than gluten yeast dough), but if you pinch a tablespoon of dough off an set it on the surface, it should hold its shape. If it doesn't, add 2-4 more tablespoons of tapioca starch until it's a little less soft and holds its shape.
7. Sprinkle your surface with tapioca starch. Using a tapioca starch covered hands or spoon, scrape the dough out onto the surface and sprinkle it well with tapioca starch on top too. Roll your dough out to an 11x16 rectangle.
8. Brush the dough with 4 tablespoons of the filling butter, reserving 1/2 tablespoon for brushing on top. Sprinkle the cinnamon sugar filling over the surface.
9. Starting with the long edge, tightly roll up the dough into a spiral. I use a bench scraper to help me roll it to make sure it doesn't stick to the surface. If you need to add more tapioca starch on the spiral as you roll, that's fine! It will just make your filling a little gooier, which, in my opinion is good.
10. Tap in the edges so they're flat or cut the edges off and use a ruler to divide your log into 9 equal pieces (about 1.75 inches long). Cut into spirals using one of two methods: 1. Use uncoated dental floss or 2. A serrated knife with very gentle back and forth movements and no downward pressure. Place your cut rolls face up in the prepared pan. Brush tops with remaining butter. Cover the pan with plastic wrap and let rise in a warm draft-free place for 1.5 hours until it has doubled in size and the cinnamon rolls are kissing each other. I let mine rise in the "proof" setting of my oven. At this point, you can also put them in the fridge overnight! Note: Your rolls WILL appear cracked on the top. This is normal and okay because it affects the taste none and you're definitely going to cover that up with icing.
11. If you chilled your cinnamon rolls overnight, remove them from the fridge and allow them to sit on the counter for 30 minutes. Preheat the oven to 350°F. Bake the rolls for 40-45 minutes, until they're firm to the touch (and if you have a meat thermometer, the bottom third of the rolls reads at least 205°F.).
12. While the rolls bake, prepare the glaze. Mix the cream cheese and butter in the bowl of a stand mixer until smooth. Add the powdered sugar and salt and mix until combined. Add 1 tablespoon milk and the vanilla extract. Add more milk as desired until you get your desired consistency. I make mine halfway between thick frosting and drizzle-able icing.
13. When the rolls come out of the oven, cover them in icing and serve warm! Cinnamon rolls are best served warm fresh out of the oven and will become more dense the longer you wait. If you don't eat them right away, you can reheat leftover buns in the oven for 5-10 minutes at 375°F or for 45 seconds in the microwave.