Preheat oven to 350°F. Spray bundt cake pan with cooking spray
In large bowl, whisk together banana, sugar, brown sugar. Beat in egg, vegetable oil and vanilla extract. Slowly whisk in the flour, baking soda and baking powder, until there are no lumps. Fold in pecans.
Fill pan with half of the batter. Add 2/3 of the Nutella, trying not to let it come in contact with the pan (so just let it float in the middle of the batter). Add the rest of the batter on top, covering all the Nutella
Bake for around 40-50 minutes, or until a toothpick inserted in the center comes out clean (it'll be golden brown).
Allow to cool, flip onto a dish. Take 1/3 cup of Nutella and microwave it for 30 seconds. Place in a piping bag or a Ziplock with with a small bit of the corner cut off. Drizzle to your heart's content! Dust with powdered sugar and serve!