Combine oats and milk in a small bowl. Set aside to soak for 20 minutes. Preheat the oven to 375 degrees F and prepare a muffin pan with cupcake liners
In a small bowl, whisk together the flour, baking powder, baking soda, salt and set aside In another bowl, thoroughly mix melted butter and sugars. Add vanilla extract, eggs and mashed banana.
Slowly pour the dry mixture into the wet ingredients and stir. Add the oats and milk. Coat the blueberries in flour before adding to the batter
Fill muffin cups to the top with batter. Bake for 18 to 23 minutes. Allow to cool before serving.