Preheat oven to 350° F and spray loaf pan with non-stick cooking spray.
In the bowl of a stand mixer, or using electric mixer, cream together peanut butter and both sugar until combined. Beat in eggs, milk and vanilla extract. Stir in sour cream.
Add flour, baking powder, and salt and mix until just combined.
Pour evenly into loaf pan and bake at 350° F for 50-60 minutes or until toothpick inserted in center comes out clean.
Remove from oven and cool completely before enjoying!