Preheat the oven to 400 Degrees.

In an 8" square baking dish, toss together the sliced bananas, 1 TBSP butter chunks and brown sugar.

Roast for 35 minutes, stirring after 17 minutes.

Cool slightly.

Reduce the oven temperature to 350.

Place the walnut halves on a rimmed baking sheet and toast for 8 minutes. You will be able to smell them when they are done. Let cool.

When the toasted walnuts are cool, finely chop some until you get 1 cup of chopped nuts and rough chop the remainder for on top of the cake. Set aside.

Preheat the oven to 375 F.

Spray a 9x13 cake pan with baking spray and set aside.

In a medium mixing bowl, whisk together the flour, baking soda, and baking powder. Set aside.

In another medium mixing bowl, whisk together the buttermilk, cooled banana mixture, and vanilla extract.

Place 1/2 cup butter and the sugar in a large bowl, beat with a mixer at medium speed until light and fluffy, 3-5 minutes.

Add eggs to the sugar mixture and mix well.

Add half the flour mixture to the batter and mix until just combined.

Add the banana mixture to the batter and mix to combine.

Add the remaining flour mixture and the finely chopped walnuts and mix until just combined.

Pour the batter into the prepared 9x13 cake pan.

Bake for 20 minutes, or until a toothpick inserted in the middle comes out clean.

Cool completely on a wire rack before frosting.

To prepare the frosting, melt the 1/4 cup butter in a small saucepan over medium-heat, cooking slowly for 4 minutes or until it becomes lightly browned (watch it, it will burn fast!)

Cool the butter slightly.

Combine the browned butter, powdered sugar, cream cheese and vanilla in a medium bowl and beat with a mixer until smooth.

Spread the frosting over the cooled bars and sprinkle the tops with the toasted walnuts.

Enjoy!!! :)