Preheat the oven to 350 degrees Fahrenheit and spray two 6" cake pans with cooking spray.
In a stand mixer with beater attachment, add the bananas, applesauce, egg whites, nut butter, sucanat, erythritol, almond milk, stevia extract, cinnamon and salt.
In a small bowl, whisk together the oat flour, peanut flour and baking powder. Slowly add to the stand mixer and beat on medium speed for 20 seconds (batter should look like a thin muffin batter or thick cake batter).
Pour batter into prepared pans and bake for ~48 minutes, or until the surface has risen, is firm to touch and springs back when tapped.
For the Frosting:
In a large bowl, whisk together the almond milk, caramel sauce, stevia and vanilla paste.
Whisk in the protein powder. Frost the cooled cakes and refrigerate for 30 minutes. Slice and serve!