This marbled Nutella banana bread is the perfectly moist and delicious banana bread we all love, with the addition of a tasty marbled Nutella swirl.
Preheat your oven to 350 degrees F and line an 8 1/2" x 4 1/2" loaf pan with parchment paper.
In a large bowl, mash the bananas with a large fork until smooth with only a few clumps remaining. Add the brown sugar, melted and cooled butter, vanilla, and eggs to the bowl. Stir mixture with a fork until just combined.
Add half the flour, baking soda, and salt to the banana mixture and stir until most of the flour is no longer visible. Add the remaining flour and stir until combined, be careful not to overmix.
Remove 3/4 cup (188g) of the banana bread batter from the bowl and pour it into a small mixing bowl. Add the Nutella to the small bowl and stir to combine.
Spoon a thin layer of banana bread batter into the prepared loaf pan. Add a layer of the Nutella banana mixture on top and continue alternating the layers until you've run out of both batters. Using a sharp knife, draw 2-3 figure 8's along the top of the loaf to create your marbled effect. If you do too many, the swirls will appear muddled.
Bake the banana bread for 60 minutes or until a toothpick comes out clean. Let rest in the pan for 10 minutes before turning out on to a cooling rack to cool completely before slicing.