Position a rack in the center of the oven and preheat the oven to 400°F. Lightly coat 2 nonstick miniature muffin pans (12 mini-muffin tins per pan) with olive oil cooking spray.
In a medium bowl, combine the bran (you can use either wheat or oat bran), flour, flaxseed, baking soda, cinnamon, and salt. Set aside. In another medium bowl or a blender, combine the milk, honey, banana, egg, olive oil, and vanilla extract until smooth.
Make a well in the center of the dry ingredients and pour in one third of the liquid mixture. Using a spoon, stir until smooth. Add the remaining liquid mixture and stir until well combined. Add the blueberries and stir again, but don't overmix.
Spoon 2 tablespoons of batter into prepared muffin cups. Bake for about 8 minutes, or until the tops spring back when pressed gently in the centers. Do not overBake. Cool the muffins int he pan on a wire rack for 10 minutes before removing from the cups. Serve warm, or allow them to cool completely on the rack. These freeze well too.