Preheat your oven to 180℃ (fan oven)/ 350℉.
Cream the butter together with the sugar, and then break in the eggs and mix well.
115 g unsalted butter, 170 g caster sugar (superfine sugar), 2 medium eggs
Stir in the bananas.
3 ripe bananas
Add the flour, baking powder and salt. Stir till well combined but don't over mix.
2 tsp baking powder, 300 g plain flour (all-purpose flour), 1 pinch of salt
Put the mixture in a greased cake tin. I used a deep 8 inch tin.
Drop in the spoons of Nutella and use a knife to marble it in the cake batter.
5-6 teaspoons Nutella
Bake for around 45-50 mins or until a skewer comes away clean. If it browns too much on top, cover the cake with foil for the last ten minutes.