Step 2: Combine the Peanut Butter and Milk
In a medium saucepan or mixing bowl, combine the peanut butter with one cup of the milk. If using a saucepan, warm gently over low heat while stirring — this makes the peanut butter loosen and become smooth and pourable, which makes it much easier to blend with the flour. Alternatively, microwave the peanut butter for 20 to 30 seconds before adding the milk and stirring. The mixture should be uniformly smooth and fluid before proceeding.
Step 3: Mix the Batter
Place the flour in a large bowl and make a well in the center. Pour in the peanut butter and milk mixture. Add the remaining three-quarter cup of milk a little at a time, stirring with a wooden spoon or sturdy fork after each addition. Continue until a thick, heavy batter forms — it should be dense but evenly moistened, with no dry pockets of flour remaining. The batter is considerably thicker than a typical quick bread batter; this is correct. It will not pour so much as scoop. If it seems too dry to come together, add another tablespoon or two of milk. If it seems loose or wet, sprinkle in an additional tablespoon of flour and stir again.
Step 4: Bake
Scrape the batter into the prepared loaf pan. Use the back of a spoon or a wet spatula to press it firmly into the corners and smooth the top as flat as possible. The batter will be rustic-looking and thick — that is exactly right. Place in the preheated oven and bake for 45 to 55 minutes, until the top is set and firm to the touch and a toothpick or thin knife inserted into the center comes out clean. The loaf will not rise dramatically — it is not meant to. It will firm up and develop a slightly darker surface as it bakes. Begin checking at 45 minutes; ovens vary and a few extra minutes either way will not harm the loaf.
