Preheat oven to 350 degrees F. Coat a 24-cup mini muffin tin with cooking spray.
Pulse oats in a blender until finely ground. Add baking powder, baking soda and salt; pulse once or twice to combine. Add applesauce, brown sugar, oil, water, flaxmeal and vanilla; puree until smooth. Stir in blueberries. Divide the batter among the muffin cups.
Bake the muffins until a toothpick inserted in the center comes out clean, 25 to 28 minutes. Cool in the pan on a wire rack for 10 minutes, then turn out to cool completely.