Preheat the oven to 325 degrees. Line a standard muffin pan with cupcake liners.
In a large mixing bowl, beat egg whites with an electric mixer until stiff peaks form.
In another large mixing bowl, beat egg yolks with an electric mixer until they start to lighten in color (about 2 minutes). Add SunButter, sliced bananas, salt, vanilla, and honey. Mix until well blended and the bananas are incorporated. Some small chunks of bananas are OK.
Take a large spoonful of the egg whites and mix it into the SunButter mixture with a rubber spatula. Add the SunButter mixture into the egg whites and fold in well. You want to mix until no more white streaks are visible. Fold in 1 cup of chopped walnuts, if using.
Fill muffin baking papers until almost full. If using nuts, sprinkle additional ½ cup over the tops of the muffins. Bake for 25 minutes or until golden brown and set and a toothpick inserted comes out clean.