Preheat the oven to 350F degrees and prepare two muffin tins with cooking spray or cupcake liners
Whisk together 1 box butter pecan cake mix, ½ cup all-purpose flour, and ½ teaspoon baking powder in a large mixing bowl.
Stir in 3 large ripe bananas, mashed, 2 large eggs and 1 cup chopped walnuts.
Mix only for about 1 minute or until everything is just combined.
Scoop the muffin mix into the prepared muffin tins, filling each about ⅔ full with batter. Do not overfill.
Sprinkle 1/2 cup chopped walnuts over the top of the muffins.
Bake for about 17-20 minutes on the middle rack or until the top turns golden brown and a toothpick inserted into the center comes out clean.
Cool for 5 minutes before removing from the muffin tins and serving warm or placing on a cooling rack to cool completely.
Notes
Please refer to my FAQ’s (Frequently Asked Questions) and ingredient list above for other substitutions or for the answers to the most common questions.