Combine all ingredients and only 3 1/2 cups of all-purpose flour in the stand mixer with the dough hook (reserve 1/2 cup flour for later).
Once the ingredients are combined turn on the stand mixer. At this point, the dough should look very wet and soggy. Grab the 1/2 cup of flour, sprinkle a little into the bowl, and begin mixing again. Do this until the dough comes together and pulls away from the sides of the bowl. (For me this typically happens around 3 3/4 cups of flour).
Once the dough is the right consistency turn the mixer to medium speed for 10-15 minutes and let it knead the dough.
Grease a large bowl with butter, and once the kneading is complete transfer the dough to this greased bowl. Cover it with plastic wrap, a wet tea towel or a plate to prevent the dough from drying out.
Set aside and let bulk rise for 8-12 hours, or until it doubles in size.
Once the dough has doubled in size, dump it onto a floured surface and roll it into a rectangle shape.
In a small bowl combine 1-2 tsp cinnamon, 2 tbsp flour, and 1/4 brown sugar and mix.
Spread the cinnamon mixture on the sourdough rectangle, reserving about 1/3 of the mixture.
Fold over 1/3 of the sourdough with the cinnamon mixture toward the center of the rectangle.
Next, fold the other 1/3 of the sourdough with the cinnamon mixture on it on top of the first fold.
Now spread the remaining cinnamon mixture on the folded sourdough.
From the short side begin to roll the dough into a log shape. Make sure to pinch the seams to prevent the cinnamon brown sugar from bubbling out.
Transfer to a buttered 9x5 loaf pan.
Once you have the dough in the greased loaf pan cover it with plastic wrap or a wet tea towel and set it aside to rise again for 2-4 hours. (I only let this loaf rise for 1 hour because it was so hot.)
After it has rose a second time preheat the oven to 375F.
Remove plastic or tea towel and bake for 40-45 minutes.
Remove and let cool when it is golden brown on the top.