Combine 5.5 oz Bread flour, 1.25 Whole wheat flour, 1/2 tsp instant yeast, 11/2 tsp honey, 11.2 oz water at room temp. Mix until smooth, the consistency of pancake batter. In a separate bowl mix 10.3 oz bread flour and 1/2 tsp instant yeast. sprinkle this over the batter and let sit for 1-4 hours.
Sprinkle 1 1/2 tsp salt and mix dough to combine. Knead for 5 minutes and then rest for 10 minutes. Knead for another 5 minutes. Transfer to a bowl and let rise until doubled. Scrape down and deflate dough, let rise again until doubled.
Preheat oven to 475. Add an oven-safe skillet to the bottom rack. Remove the dough from the bowl and shape into a ball. Let rise a final time, about 1 hour.
Gently make a 1/2 inch slash in the top of the dough with a sharp knife or razor. Place the bread in the oven and toss 1/2 cup of ice cubes into the skillet.
Bake for 10 minutes and then lower the oven to 425 and continue for another 20-30 minutes, until deep golden brown.