1. Preheat your oven to 350 degrees F.
2. Combine flour, baking powder, and salt; set aside.
3. In a large bowl, cream butter and sugar.
4. Add peanut butter and mix well.
5. Add beaten eggs and vanilla, beat until creamy.
6. In alternating batches, add in dry ingredients and milk. Beat until light and fluffy.
7. Spoon batter into pan lined with paper cups.
8. Bake for 20 minutes, or until a toothpick comes out clean when inserted into the center of a cake.
9. Let cool, decorate, and enjoy!