Preheat oven to 350 degrees. Prepare a 9×13 baking dish with non-stick spray.

In a large bowl, mix together the sugar, bananas, oil and eggs until the mixture is smooth and creamy. Stir in the flour, baking powder, baking soda, salt and cinnamon. Stir in 1/2 cup of the walnuts.

Spread the batter in the prepared pan and bake for 25-30 minutes, until a toothpick comes out clean. Cool completely before frosting.

While the cake is cooling Cream together the cream cheese, butter and vanilla. Slowly add in the powdered sugar and mix until a thick frosting forms.

Dollop the frosting all over the banana bars and carefully spread it to the edges. Top with the remaining 1/4 cup walnuts, cut and enjoy!