Preheat the oven to 350ºF. Line a 12 cup muffin tin with liners or grease each cup well.
In a blender or food processor, pulse the nut butter, egg, and bananas until combined.
Add the almond flour, collagen, baking soda, spices, and vanilla, and continue to pulse until the batter is smooth & well incorporated.
Scoop the batter into the lined muffin tin, and transfer to the oven. Bake for 12 to 18 minutes, or until set.
Allow the muffins to cool, and work on your frosting.
To a blender, add all of the frosting ingredients. Blend until smooth & creamy.
Spread the frosting over the cooled muffins and serve!