Directions
Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners.

In a medium bowl, whisk together the flour, baking soda, and salt.

In a large bowl, combine the mashed bananas, sugar, melted butter, egg, and vanilla extract. Mix until smooth.

Gradually add the dry ingredients to the wet ingredients, stirring until just combined.

In a small bowl, mix together the cocoa powder and milk until smooth.

Divide the batter in half. Stir the cocoa mixture into one half of the batter.

Alternately spoon the banana and chocolate batters into the muffin cups, filling each about 3/4 full.

Use a toothpick to gently swirl the two batters together in each muffin cup to create a marbled effect. Sprinkle chocolate chips on top if desired.

Bake for 18-22 minutes, or until a toothpick inserted into the center of a muffin comes out clean.

Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.

Variations & Tips

For a nutty twist, add 1/3 cup of chopped walnuts or pecans to the batter. If you’re a fan of spices, try adding a teaspoon of cinnamon or a pinch of nutmeg to the banana batter for an extra layer of flavor. To make these muffins gluten-free, substitute the all-purpose flour with a gluten-free flour blend. You can also make a vegan version by using flax eggs (1 tablespoon flaxseed meal + 2.5 tablespoons water per egg) and coconut oil instead of butter.