Preheat the oven to 375°F (190°C). Line a 12-cup muffin tin with paper liners and set aside.
Mix dry ingredients
In a large mixing bowl, whisk together the flour, granulated sugar, baking powder, baking soda, cinnamon, and salt.
2 cups all-purpose flour, 1 cup granulated sugar, 3 teaspoons baking powder, ½ teaspoon baking soda, 1 teaspoon ground cinnamon, ½ teaspoon salt
Mix wet ingredients
In a separate large mixing bowl, whisk together the mashed banana, Greek yogurt, oil, eggs, and vanilla extract until smooth and fully combined.
1 cup mashed banana, ¾ cup Greek yogurt, ½ cup oil, 2 large eggs, 1 teaspoon vanilla extract
Combine wet and dry
Pour the wet mixture into the bowl of dry ingredients. Mix until just combined — stop as soon as no streaks of flour remain. Fold in the chocolate chunks.
1 cup chocolate chunks
Bake
Divide the batter evenly among the 12 muffin cups.
Bake for 20 minutes, or until the muffins spring back when lightly pressed in the center, or a toothpick comes out clean with a few moist crumbs.
Cool
Let the muffins cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.
Notes
Don’t overmix: Overmixing leads to dense muffins. Stir only until the flour disappears.
Mix by hand: Muffin batter is best mixed by hand.
Check doneness: Press lightly in the center or test with a toothpick.
Perfect rise tip: For extra-tall bakery-style muffins, bake at 425°F (220°C) for 5 minutes, then reduce the temperature to 350°F (180°C) and bake for 12–15 minutes.
Easy portioning: A cookie scoop evenly divides the batter.
Storage: Store muffins in an airtight container at room temperature for up to 3 days.
Freezing: Freeze in an airtight container for up to 3 months. Thaw at room temperature before serving.