Heat oven to 400º F. Coat a muffin tin with cooking spray or line with paper liners.
In a small bowl, combine buttermilk and oats. Let soak for 5 minutes.
Meanwhile, stir together flour, baking powder, baking soda and salt in a medium mixing bowl.
In a large mixing bowl, whisk the egg with a fork. Add brown sugar, milk & oat mixture and melted coconut oil to the egg.
Gently fold flour mixture into the wet ingredients until just combined. Don't over mix! Fold in blueberries.
Fill muffin tins 2/3 full. Bake for 18-20 minutes.