Preheat oven to 350°F (175°C). Grease a muffin tin or line with paper liners.
In a large bowl, mash the bananas.
Add the eggs, melted butter, milk, and vanilla extract. Mix well.
In another bowl, combine the gluten-free flour, sugar, baking powder, baking soda, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Gently fold in the blueberries.
Divide the batter evenly among the muffin cups.
Bake for 25 minutes or until a toothpick inserted into the center comes out clean.
Let cool before serving.