Preheat your oven to 350°F (175°C). Grease a loaf pan.
In a mixing bowl, whisk together the peanut butter and sugar until smooth.
Add the eggs one at a time, beating well after each addition.
Stir in the milk until combined.
In another bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Pour the batter into the prepared loaf pan and smooth the top.
Bake for 60 minutes, or until a toothpick inserted into the center comes out clean.
Let the loaf cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.