Preheat oven to 375 degrees.
Line a muffin pan or spray with cooking oil.
Combine oats, flour, sugar, baking powder, baking soda, and salt.
In a heavy dish mash bananas.
Whisk together bananas, butter (don't forget to melt it!) and eggs.
Add wet ingredients to dry ingredients and stir just until dry ingredients are moistened.
Gently fold in the blueberries.
Divide batter among muffin cups - it should make 12 muffins.
Bake for 20 minutes or until toothpick inserted into the centre of a muffin comes out clean.
Let muffins cool in pan for a few minutes before transferring to wire rack.