In a blender, blend banana, milk, vanilla and sugar on high until completely smooth.
In a large bowl, whisk oat flour, almond meal, gluten-free flour and baking powder together then pour the wet mixture into the bowl and stir to combine well. Stir in sprinkles.
Add the batter into a muffin pan filling each about ¾ way to the top.
Bake for about 22 minutes. Allow to cool for 30 minutes before removing from the pan.
Optional: once cooled, add frosting on top and extra sprinkles!