In a small mixing bowl, whisk together the sugars and cinnamon. Set aside.
TO MAKE THE BREAD:
Preheat oven to 350 degrees and grease a standard 9"x5" loaf pan.
In a large mixing bowl, whisk together the sugar, gluten free flour, baking powder, and salt. Make a well in the center of the mixture.
In a medium mixing bowl, beat the egg. Add the milk, butter, and vanilla and stir until combined. Transfer the egg mixture to the well of the flour mixture and stir until just combined.
Pour half of the batter into the prepared pan. Sprinkle half of the cinnamon mixture over the batter. Pour the remaining batter over the cinnamon layer and top with the remaining cinnamon mixture.
Using a table knife or spatula, draw lines through the batter, vertically and then horizontally, to swirl the mixtures together.
Bake for 50-60 minutes or until the bread is browned and a pick inserted into the center comes out clean.
Cool the bread in the pan for 10 minutes. Remove the bread from the pan and allow to cool completely on a wire rack.
Notes
Check the ingredients of your gluten free flour mix for xanthan gum. If your flour mix doesn’t contain it, try adding ½ teaspoon to the recipe. I used Bob’s Red Mill Gluten Free 1 to 1 Baking Flour which contains xanthan gum.
Be sure to check the bread, with a cake tester or wooden pick, prior to removing from the oven. Test the bread in the middle of the loaf to ensure the thickest part of the bread is done.
The cinnamon bread will last for 3-4 days stored at room temperature in an airtight container. You can also store the bread in the freezer for up to 3 months. Tightly wrap the bread in plastic wrap and then place in a freezer-safe bag.