Preheat oven to 350°F (180°C). Line a muffin tin with paper liners or grease. Set aside.
In a large bowl, whisk together flour, oats, baking soda, salt, and nutmeg.
In a separate bowl, stir together maple syrup, melted butter, mashed bananas, and vanilla extract.
Add the wet ingredients to the dry ingredients; stir until just combined (be careful not to over-mix the batter). The batter will be slightly lumpy, which is fine!
Gently fold the blueberries into the batter.
Divide the batter evenly among the prepared muffin cups. The muffins do not rise very high, so be sure to fill the muffin cups pretty full!
Bake for about 30 minutes, or until a toothpick inserted in the center comes out clean.