Combine the first 5 dry ingredients into a bowl and whisk together thoroughly.
Take the bananas, melted butter,bvanilla, egg and sugars and mix together until the sugar is dissolved. Now let's remember that I have an affinity for fake banana flavoring. I know, it's a sin. I'll also confess that I love, love, LOVE those fake yellow banana marshmallow candies in the bag that seem to be everywhere during the summer. One of my favorite treats. So it was a natural progression that I really wanted a huge banana flavor to these muffins to go with the peanut butter. You choose your poison. Mild, natural banana flavor or one enhanced by a half tsp of banana flavoring. I think they rock with the flavoring.
Take the dry ingredients and add them into the wet, mixing until they are just combined.
Add in the peanut butter cups and stir until they are mixed throughout the batter. The baking PB cups are small enough that they are almost just like a chocolate chip, so I would definitely try to find this type for these muffins.
Using an ice cream scoop, fill 12 muffin tins up evenly. The scoop will give you a beautiful rounded dome top like you see in the pictures below.
Bake at 375 degrees for 15-17 minutes, until they are browned on top and baked through completely.