Preheat your oven to 350°F (175°C).
In a medium bowl, mash the ripe bananas thoroughly until smooth.
Add the vanilla protein powder to the mashed bananas.
Mix well until a thick, uniform batter forms.
Line a muffin tin with 6 paper liners or grease it lightly.
Divide the batter evenly among the muffin cups.
Bake in the preheated oven for 15 minutes or until the muffins are set and a toothpick inserted in the center comes out clean.
Remove the muffins from the oven and allow them to cool in the tin for 5 minutes.
Transfer the muffins to a wire rack to cool completely before serving.