Preheat your oven to 350°F (175°C) and grease a standard loaf pan or line with parchment paper.

In a mixing bowl, peel and mash the ripe bananas until smooth. Incorporate melted unsalted butter, stirring to combine. Add the eggs and sugar, mixing until uniform.

In another bowl, sift together the flour, baking soda, and salt. Slowly fold into the wet mixture without overmixing.

Dollop softened Nutella over the batter and swirl gently with a knife to create a marbled effect.

Pour the batter into the loaf pan, smoothing the top. Bake for 55-65 minutes, checking for doneness with a toothpick.

Remove from the oven, cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.