Preheat oven to 350℉, and lightly grease a 12-cup muffin tin with butter or non stick cooking spray
In a large bowl, add the eggs, and beat slightly
Add the bananas, and mash well
Add the milk, vanilla and melted butter
Add the flour, sugar, baking powder, baking soda, cinnamon and salt, and stir the batter until just combined. Don't over mix -- a few lumps are fine
Sprinkle 1 teaspoon flour over the berries, and toss to coat
Gently fold in the blueberries
Scoop the batter into the muffin tin, and sprinkle the crumb topping evenly on top of the muffins
Bake for 20-25 minutes or until toothpick inserted into center of the muffins comes out fairly clean. Should not be wet, but a few crumbs are fine
Allow to cool slightly, then remove from the pan to finish cooing on a wire rack or platter