In the bowl of a stand mixer, mix together the dry ingredients.
Add the buttermilk and molasses into the bowl and beat for 30 seconds on low speed.
Stop machine and scrape batter down. Beat for 2 minutes on medium.
Set batter aside for 30 minutes.
Preheat oven to 325° F. Adjust oven racks so that the bread will bake on the lowest one. Grease or spray an 8" x 4.5" loaf pan with cooking spray.
Spread the batter evenly into the prepared pan and smooth the top.
Cover this pan with a piece of foil.
Use either a Dutch oven or a 9" x 13" baking pan as a steamer box for the bread to bake in.
Place the baking pan into the 9" x 13" pan.
Add about 6 cups of water to the baking pan or Dutch oven.
Cover the whole pan with another sheet of foil.
Carefully place the pan into the oven and bake for 90 - 100 minutes or until an instant read thermometer registers 195F.
Use caution when removing the foil as the steam will be very hot and will come out very fast. Remove the loaf pan from the steamer and let it cool on a wire rack for 10 minutes.
Remove the bread from the pan and enjoy!
Video
Notes
Mix the batter on medium speed for the full 2 minutes.
Set the batter aside to rest for 30 minutes before pouring into baking pan.
Cover both pans with a sheet of foil each.
Water should be enough to fill the pan and come up the sides.
Be very careful when removing the foil as the hot steam can burn.