Preheat oven to 350 degrees Fahrenheit. Grease and lightly flour a 9″x 13″ cake pan knocking off any excess flour and set aside.
In a medium bowl, whisk together flour, baking powder, baking soda and salt and set aside.
Using an electric mixer in a large bowl cream butter and sugar on medium speed until creamy. Add eggs one at a time on low speed until combined. Stir in vanilla and bananas. Gradually add in flour mixture alternating with milk until both are combined. Do not over mix. Pour batter into prepared pan and bake on center rack for 35-40 minutes until cake tester in the center of the cake comes out clean.
Allow cake to cool completely before frosting.
Nutella Frosting
Using an electric mixer beat butter and nutella until combined. Gradually add in confectioners sugar until of confectioners sugar is combined. Mixture will be crumbly. Add in 2 tablespoons of milk and beat on medium-high speed. Add in additional milk until frosting reaches a spreadable consistency.