In the bowl of a stand mixer fitted with a dough hook, stir together buttermilk, 1/2 cup water, honey and yeast. Allow to ferment for 5-6 minutes until frothy. Add whole wheat flour, 1 cup bread flour, cooked cereal, butter and salt. Stir to combine. Add 1/2 cup bread flour and begin kneading until flour is absorbed. Continue adding bread flour by the 1/4 cup until dough is supple and pulls away from the bowl, approximately 7-9 minutes.