Peanut Butter and Chocolate Banana Muffins

Preheat oven to 425 degrees Fahrenheit. Line a 12-cup muffin pan with muffin liners or parchment paper. Lightly spray with cooking spray.
In a large bowl, whisk together the dry ingredients: flour, baking powder, baking soda, salt, and brown sugar. Set aside.
In a medium bowl, mash bananas then add melted butter, vegetable oil, buttermilk, peanut butter, eggs, and vanilla. Whisk all together until combined.
Make a well in the center of the dry ingredients then add the wet ingredients. Using a spatula, gently fold the dry mixture into the wet mixture and continue until the batter is formed and everything is just incorporated. Stir and fold in the chocolate chunks.
Using a large cookie scoop, fill the muffin cups 3/4 of the way full and add more chocolate chunks on top, if desired. Using the extra peanut butter, put about 1/4 teaspoon of peanut butter in the center then using a toothpick, gently swirl and drag the peanut butter through the top of the batter. Repeat for all muffins.
Bake at 425 degrees for 5 minutes then take down the temperature to 400 degrees and bake for an additional 13 minutes, or until a toothpick inserted into the center comes out clean.
Let cool in muffin pan for 10 minutes then remove muffins and place on a wire rack to cool completely.
Store in an airtight container for up to 5 days.