Preheat the oven to 425 degrees F. Prepare a muffin pan with cooking spray or muffin liners.
Add the bananas to a large mixing bowl and mash with a fork (I like leaving a few small clumps). Then add the applesauce, syrup, oil, egg and vanilla and mix until well combined.
Add the flour, protein powder, cornstarch, cinnamon, baking powder, baking soda, salt and pecans (if using).
Mix in the dry ingredients until they are incorporated. Do not over-mix!
In a separate bowl, combine the butter and brown sugar with a fork. Add the flour and pecans and mix until crumbly and mostly combined.
Spoon the batter into the prepared muffin pan. Sprinkle the muffins evenly with the pecan crumble.
Bake muffins for 5 minutes at 425 F, then with muffins staying in the oven, reduce heat to 350 F. Bake muffins here for 13-15 minutes more.
Remove from oven and allow to cool in the pan for a few minutes before transferring to a wire rack to cool completely. Serve with cream cheese, if desired, and enjoy!