Preheat the oven to 350°F (180°C) and prepare a 2-cup muffin pan.
In a large bowl, mash 3 large ripe bananas until mostly smooth. Add 1 large egg, ½ cup Greek yogurt, ¼ cup honey, and 2 teaspoons vanilla extract. Mix well.
Add 1½ cups all-purpose flour, 1 cup rolled oats, 2 teaspoons baking powder, ½ teaspoon baking soda, ½ teaspoon cinnamon, and 1 pinch salt. Stir gently until just combined. Do not overmix.
Gently fold in 1½ cups blueberries so they don’t break.
Spoon the batter into the liners, filling them all the way to the top.
Bake at 350°F (180°C) for 22 minutes, until a toothpick inserted in the center comes out mostly clean.
Let the muffins cool in the pan for 5 minutes, then move them to a rack. Let cool completely before removing the liners.
