Preheat oven to 356F and prepare a muffin tray or mini-muffin tray.
Melt the butter (about 20 seconds in the microwave).
Add the ripe bananas, eggs, raisins, and melted butter to a blender and blend until smooth.
Combine the oat flour, all-purpose flour, baking powder, and cinnamon in a medium mixing bowl.
Whisk the dry ingredients until combined.
Pour the blended wet ingredients into the dryingredients bowl and whisk until combined.
Scoop the muffin batter into the muffin tray and bake for 20 minutes until a toothpick comes out clean and the muffins are golden on the edges.
Let them cool a bit and move to a wire rack.