Combine oats and milk and allow to sit for around 15-20 minutes.
Whisk the flour, baking powder, baking soda, cinnamon, and salt together in a large bowl.
In a separate bowl add the egg, brown sugar, vanilla, and butter and stir to combine.
Add the wet ingredients to the dry ingredients along with the oats and milk and stir a few times until just combined. then fold in the blueberries gently.
Add the batter to a greased muffin pan filling each cup around ¾ of the way.
Bake for 18-22 minutes or until a toothpick inserted in the center comes out clean.
Allow to cool on a wire rack for 5 minutes before serving.