Measure all the ingredients in a mixing bowl, -or bread machine canister if you're using one- and mix with a dough hook on low speed for 10 minute. If you're using a bread machine then simply set it on the dough setting until the cycle is complete. After it's finished mixing, place the dough in a bowl and cover with cling wrap and let in sit for 6 hours at about 70°.
After 6 hours, dump the dough onto your work surface and divide into two loafs. The dough should be sticky but workable. If it's to sticky to work with then wet you hands slightly, but do not add flour. Stretch the dough out into a rectangle and fold it like a letter, then roll it up from the short end. Then taking both hand, with your pinkies resting on the work surface, pull the ball of dough towards you rotating it as you go. Repeat until you get a smooth tight ball. Let it rest for 20 minutes to help seal the seam. After 20 minutes lift dough up with a bench/dough scraper and place in banneton baskets. Cove and let them rest an additional two hours and then move them to the fridge over night.
On baking day, preheat the oven to 550℉ and place your dutch oven in while it preheats. In the mean time, flip your dough out on to a sheet of parchment paper and score it. Once oven is up to temperature lift the dough by the parchment paper and set into the dutch oven. Drop the ice cubes into to the pot between the parchment paper, not directly on the dough. Cover and place in the oven. Decrease the temature to 400℉ and bake for 30 minutes. Then uncover and bake for an additional 15 minutes.
Notes
If you don't already weigh your ingredients I suggest you start. It's way more accurate, especially when working with freshly milled flour.I also highly recommend sifting your flour for this recipe. Removing all the big flakes of bran will give it a more open crumb, and structured loaf. I perched a set of fine mesh ones on amazon.