Combine the all purpose flour, whole wheat flour, oats, yeast, vital what gluten, rosemary, garlic powder, and salt in a large bowl. Mix together until fully combined.
Make a well in the center of the mixture and pour in the water. Stir until you don't see any white flour patches. The dough should be sticky and shaggy. If the mixture is too dry, add and additional 1-2 tbsp of water (up to ¼ cup) to the dough.
Cover the bowl with plastic wrap or a towel and put it in a warm place for 12-18 hours. I usually do this step overnight.
Preheat the oven to 450 degrees.
Put the pot in the oven with the lid on to warm for 30 minutes. While the pot is warming, punch down the dough, and fold it 3-4 times to get rid of any air bubbles. Cover again and let it rise for 30 minutes while the pot is heating up.
Carefully remove the pot from the oven. Take off the lid, put a piece of parchment paper in the pot, and sprinkle wheat bran into the pot. Scrape the dough out of the bowl and put it into the hot pot. (Optional) If you want to add a topping, you can sprinkle 1 tbsp of oats and 1 tbsp of shredded vegan parmesan cheese over the top to give it that bubbly, baked-on cheese look.
Replace the lid and put the pot into the oven to bake for 40 minutes covered. Remove the lid and let it cook for 10 minutes or until the crust is golden brown.
Remove the pot from the oven. Lift the bread out by grabbing both sides of the parchment paper. Transfer the bread to a wire rack to cool for 1 hour.