First preheat your oven to 350-degrees.
Gather all your ingredients..eggs, butter, Nutella, baking powder, milk, and smushed bananas. I just used my paddle attachment in the mixer to mush em' up really quickly...Since everything was going to end up in that bowl anyhow.
Add in all your ingredients EXCEPT the Nutella.
Once combined, remove two cups of the non-Nutella mixture. Once removed add in your Nutella to the mixture IN the bowl and combine.
Grab a loaf pan that has been lined with parchment paper and buttered up! Trust me...this is essential...your bread will literally slide out. And I like to do it like you see below with the edges sticking out. That way when it's baked I just lift the paper and I can move the loaf to a cooling rack much easier.
Place the whole amount of Nutella batter in the pan and just drop the non-Nutella batter in there leaving room in between.
Take a long skewer (wooden or metal) or butter knife and swirl around. That's how you get that marble look!
Place into the oven for 55 minutes or until a toothpick comes out clean.
Lift the parchment up and the bread will come with it
Allow to cool on cooling rack for 5-10 minutes. Then slice and enjoy.