01 -
Preheat your oven to 350°F (175°C) and line a muffin tin with liners or grease it lightly.
02 -
In a large bowl, mash the ripe bananas with a fork. Stir in the melted butter until well combined.
03 -
Mix in the baking soda, salt, and sugar. Add in the beaten egg and vanilla extract, mixing until smooth.
04 -
Gently fold in the all-purpose flour until just combined, being careful not to overmix.
05 -
Spoon half of the batter into the prepared muffin tin, creating a small well in the center of each. Add about a teaspoon of Nutella into the center, then cover with the remaining batter.
06 -
Use a toothpick or knife to gently swirl the Nutella into the batter, creating a marbled effect.
07 -
Place the muffin tin in the oven and bake for 18-20 minutes, or until a toothpick inserted in the center comes out clean.
08 -
Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack.