Preheat the oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners or lightly grease the cups.
In a medium bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt.
In a large bowl, combine the mashed bananas and granulated sugar. Mix well.
Add the egg, vegetable oil, vanilla extract, and plain yogurt to the banana mixture. Stir until combined.
Gradually add the dry ingredients to the wet ingredients, stirring gently until just combined. Do not overmix.
Divide the batter evenly among the 12 muffin cups.
Bake for 18 to 20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Remove the muffins from the oven and allow them to cool in the pan for 5 minutes.
Transfer the muffins to a wire rack to cool completely before serving.