For the rolls
3 1/4 cups (455 g) all purpose gluten free flour, plus more for sprinkling
1 1/2 teaspoons xanthan gum (omit if your blend already contains it)
1/2 cup (43 g) cultured buttermilk blend powder or nonfat dry milk
2 teaspoons (6 g) instant yeast
1/4 teaspoon cream of tartar
1/4 teaspoon baking soda
2 tablespoons (26 g) packed light brown sugar
1 teaspoon (6 g) kosher salt
1 teaspoon apple cider vinegar
2 tablespoons (28 g) unsalted butter, at room temperature
1 egg (50 g, weighed out of shell) at room temperature, beaten
1 1/2 cups (12 ounces) warm water (about 95°F)
For the filling
4 tablespoons unsalted butter, at room temperature
3/4 cup (164 g) packed light brown sugar
1 teaspoon ground cinnamon
For the optional glaze
1 cup (115 g) confectioner’s sugar
1 tablespoon milk (any kind), plus more by the 1/4 teaspoonful
Grease a 9-inch x 13-inch casserole dish and set it aside.
Make the dough. In the bowl of a stand mixer fitted with the paddle attachment, place the flour, xanthan gum, buttermilk powder, yeast, cream of tartar, baking soda and sugar in the bowl of your stand mixer. Whisk to combine well with a handheld whisk. Add the salt, and whisk again to combine well. Add the cider vinegar, butter, and egg, and mix to combine well. With the mixer on low speed, add the water in a slow but steady stream. Once you have added all the water, turn the mixer up to high and let it work for about 3 minutes. The dough will be moist but continue to mix until the dough starts to pull away from the sides of the bowl in spots.
Turn the dough out onto a flat, lightly floured surface. Sprinkle it with some extra flour and knead it gently until it’s somewhat smoother. Divide the dough in half, and place one half under a tea towel to prevent it from drying out. Using a rolling pin and sprinkling lightly with flour as necessary to prevent sticking, roll the remaining half of dough into a rectangular shape about 1/2-inch thick, and about 9 inches x 12-inches.
Add the filling. Using an offset spatula or spoon, spread the softened butter all around the rectangle, leaving 1-inch border clean all around. Sprinkle with the brown sugar evenly on top of the butter and pat the brown sugar down lightly with your fingers to help it stick to the butter. Sprinkle the cinnamon evenly on top of the sugar. Starting at a short side, roll the dough tightly into a coil. Using a piece of unwaxed dental floss or thread or a very sharp knife, cut rolls in cross-section each about 2-inches wide. Place the rolls in the prepared baking pan, about 1-inch apart. Apply even pressure to the top of each roll with your fingers to compress the coil about 1/3 of the way down. Repeat the process with the other half of the dough. Cover the pan with lightly oiled plastic wrap and set in a warm, draft-free location to rise until about 150% its original size. It should take about 1 hour.
When the dough is nearing the end of its rise, preheat your oven to 350°F. Remove the plastic wrap and place the pan in the center of the preheated oven. Bake for about 25 minutes or until the cinnamon rolls are golden brown on top and cooked in the middle. Remove from the oven and let the rolls cool to room temperature.
In a small bowl, place the confectioners’ sugar and milk. Mix well, until a thick paste forms. Add more milk by the 1/4-teaspoon, mixing to combine well, until the glaze falls off the spoon slowly, in a thick but pourable glaze. Drizzle the glaze on top of the cooled rolls and allow to set briefly before serving.