Mix. Combine dry ingredients both flours, salt, and yeast together in a large mixing bowl. Make a well in the center of the dry ingredients for the water. Pour the water into the middle of the dry ingredients and mix until well combined. It will be shaggy and messy. That's okay.

Long rise. Cover the bowl and set it aside at room temp to rest for 18-20 hours. You're looking for the dough to double or triple in size with a flat, bubbly top. Depending on the ambient temperature in your kitchen, the dough may be ready a little before the 18 hour mark, or be fine slightly past the 20 hour mark.

Shape. Use a bowl scraper or your fingers to gently release the top edge of the dough from the bowl, pulling it into the center. Generously flour a clean countertop and turn the dough out onto the counter. Lightly flour the top of the dough just enough to prevent it from sticking to your hands. Fold the edges of the dough across the middle to pull it into a round shape with the edges pinched together on top. Flip the loaf over so the seam side is underneath. Cup your hands around it and lightly lift and rotate the ball of dough against the counter, tucking the dough underneath itself as you go to create surface tension on top. Dust with more flour as needed during shaping to prevent sticking.

Rest. Crumple a piece of parchment paper into a ball. Flatten it out, then crumple and flatten it out again. Use a bench scraper to lift the ball of dough onto the flattened piece of crumpled parchment paper. Dust the surface of the dough lightly with flour, cover it with a clean dish towel, and let it rise for 1-2 hours.

Preheat the oven to 450°F with a covered Dutch oven inside during the final 30 minutes of rise time.

Score and bake. Score the top of the loaf. Then, carefully remove the Dutch oven from the oven. Take the lid off and set it aside. Gather the corners of the parchment paper together, pick the dough up, and place it inside the Dutch oven. Put the lid back on the Dutch oven.

Bake. Place the Dutch oven inside the oven and bake the bread with the lid on for 30 minutes (don't peek!), then remove the lid and bake another 10-15 minutes until deeply golden brown on top.

Cool. Transfer the fully baked loaf to a cooling rack and let cool completely before slicing.