Preheat the oven to 325°F (163°C).
Grease a 9" x 5" loaf pan and set aside.
In a large bowl, whisk together the flour, baking powder, and salt.
In a separate bowl or large liquid measuring cup, whisk the peanut butter and the molasses with the milk to fully incorporate them.
Make a well in the flour mixture and pour the milk mixture into the well.
Gently mix everything together until all the flour is fully saturated and no white streaks remain. Do not over mix.
Transfer the batter to the greased loaf pan and spread it out evenly.
Place the loaf pan on the middle rack of the preheated oven and bake for one hour or until a toothpick inserted into the center of the bread comes out clean. (Note: Keep in mind that every oven is different, so I recommend checking the bread at 50 minutes to see if it is done. For example, I checked my bread at 50 minutes in my oven, and it was done.)
If at any time, the bread is not done baking but is over browning, tent the loaf pan with foil and continue baking until a toothpick inserted into the center comes out clean.
Once the bread has finished baking, use pot holders to remove the loaf pan from the oven and place it on a heatproof surface. Allow the pan to cool slightly, then remove the bread from the loaf pan and transfer it to a cooling rack.
Once the bread has cooled, you can slice and enjoy it.
Wrapped well, this peanut butter bread can stay fresh in the refrigerator for four days or in the freezer for two months.