Add the flour, salt yeast and cinnamon to a bowl and whisk together. Make a well in the center of the bowl and add the water. Use a spatula or wooden spoon to stir together until the water is incorporated. The dough will be very wet and sticky.
Cover the dough with a towel or plastic wrap and let rise overnight. Anywhere from 12-18 hours is perfect.
Preheat the oven to 450°f and place a rack in the middle of the oven. Place a piece of parchment paper on your work surface and lightly flour. Drop the dough onto the parchment paper and shape into a ball. Cover with a towel or plastic wrap and let rise for one hour.
While the dough is on it's second rise, make the cinnamon sugar topping by combining the butter, brown sugar and cinnamon.
Place your dutch oven with the lid on in the preheated oven for half an hour.
Just before baking, use the base of a wooden spoon to create the bagel hole. Dot the top of the dough with the cinnamon sugar topping.
Very carefully pull your dutch oven out of the oven and remove the lid. Grab the corners of your parchment paper and place the loaf inside the dutch oven, paper and all, and place the lid on the dutch oven. Place the dutch oven in the oven and set a timer for 30 minutes. After 30 minutes, remove the lid and continue baking for 15 minutes.
Remove the dutch oven from the oven and carefully take the loaf out of the dutch oven (I like to use a pair of tongs for this). Watch out for the molten sugar mixture. Let cool at least 10 minutes before slicing.