Preheat the oven to 375ºF. Line 15 muffin cups with liners, or spray with nonstick cooking spray.
In a large bowl, beat together the peanut butter, oil, and sugar. I like to do this for a couple of minutes.
Add in the eggs and beat until combined. Mix in the milk and the vanilla.
Add the flour, baking powder, and salt. Mix just until all of the ingredients are combined.
Divide the batter evenly between the prepared muffin cups. They should be almost full.
Bake until a tester inserted in the center comes out almost clean, with just a few crumbs, about 20-23 minutes.
Let cool slightly before serving.
Notes
Nutrition information provided as an estimate only. Various brands and products can change the counts. Any nutritional information should be used as a general guide.