Place 3 cups of water in a medium-sized pot with a heavy bottom. Bring to a boil over high heat.
Stir the multigrain cereal into the boiling water and reduce the heat to medium. Cook the cereal, stirring frequently, until the water is absorbed and cereal resembles a thick porridge. Be sure to stir the bottom well as it cooks to prevent burning.
Remove the cereal from the burner. Stir in butter, salt, maple syrup, molasses, and milk. Allow to cool slightly.
Meanwhile, place the lukewarm water and yeast in a large mixing bowl or the bowl of a stand mixer. Let stand until the yeast is frothy.
Stir the bran and one cup of all-purpose flour into the cereal.Add the cereal to the yeast and stir to blend.
Gradually add the remaining all-purpose and whole wheat flour and stir until well incorporated. Either turn out the dough onto a floured surface and knead with your hands or use the dough hook on an electric stand mixer to knead. Work the dough until it comes together in a smooth ball, adding more all-purpose flour as necessary to achieve a dough that is soft but not at all sticky. The dough should hold a ball shape and not sag when it rests.
Lightly grease a large mixing bowl and place the dough ball inside. Cover with plastic wrap and a clean dish towel. Place in a warm spot and allow to rise until doubled, at least 30-40 minutes.
Punch the dough down in the bowl and tip out onto a lightly floured surface. Knead again for a couple of minutes, then divide into 4 equal pieces. Knead each piece into a ball and place seam side down in a greased bread pan. Each pan will have two balls.
Spray two pieces of plastic wrap and lay them loosely over the bread pans. Cover with the clean towel again and place in a warm place. Allow to rise again until doubled, about 40 minutes.
Preheat oven to 350°. Carefully remove towel and plastic from the bread, then place on the middle rack in the oven. Bake for 35-40 minutes. Bread is done when tapping the top produces a hollow sound.
Remove bread from pans and place on a wire cooling rack. Allow to cool slightly (yeah, right!) before cutting. When completely cooled seal the bread in plastic bags.