Preheat your oven to 375°F. Line a muffin tin with paper liners or lightly grease each cup. This helps the muffins release easily after baking and keeps cleanup simple and quick.

In a large bowl, combine the oats, flour, baking powder, baking soda, cinnamon, and salt. Stir well until everything looks evenly mixed. This step helps distribute the ingredients properly throughout the batter.

In another bowl, whisk the eggs, brown sugar, melted butter, milk, and vanilla extract. Mix until smooth and creamy. The brown sugar adds moisture and gives the muffins a soft texture.

Pour the wet ingredients into the dry ingredients. Stir gently using a spatula until just combined. Do not overmix because that can make the muffins dense instead of soft and fluffy.

Place blueberries in a small bowl and toss them with one tablespoon flour. Fold them carefully into the batter. This little trick helps prevent the berries from sinking during baking.

Spoon the batter evenly into the muffin cups. Fill each cup about three-quarters full. You can sprinkle a few extra oats or blueberries on top for a pretty bakery-style look.

Bake the muffins for about 20 to 22 minutes. The tops should look golden and slightly firm. Insert a toothpick into the center. If it comes out clean, the muffins are ready.

Remove the muffin pan from the oven and let the muffins cool for five minutes. Transfer them to a cooling rack. Enjoy warm for the best flavor and texture.