Preheat oven to 350°F.
Add milk, eggs, sugar, and peanut butter to jar. Secure lid and select "Batter." Add salt, baking powder, and flour to jar. Secure lid and press "Pulse" 4–6 times or until flour is incorporated.
Pour batter into greased 9-x-5-inch loaf pan. Bake for 50 minutes or until wooden toothpick inserted comes out clean.
For 4 small loaves, divide batter among 4 mini loaf pans and bake for 30 minutes. Substitute 1¾ c white whole wheat flour in place of all-purpose flour.