Preheat oven to 450 degrees. In bowl of stand mixer, stir together the flours, salt and yeast, using the paddle attachment. Stir in the molasses and water. Blend to make a thick, sticky dough. Turn the mixer up to medium and beat for about 2 minutes. (The mixing can also be done by hand, with a very heavy spoon.)
Turn batter into a well-greased 8½- by 4½-inch loaf pan. Cover with plastic wrap and let rise for 30 to 45 minutes, or until the dough nearly reaches the top of the loaf pan.
Bake loaf in the middle of the oven for 10 minutes. Reduce the heat to 425 degrees and bake 35 to 40 minutes more, or until the top is richly browned and the loaf sounds hollow when tapped.
Turn out onto a rack and let cool completely before slicing.
Nutrition information per slice: