Preheat the oven to 350 degrees Fahrenheit.
Grease and line with parchment paper a 9x13 baking pan and set aside.
In a large mixing bowl, whisk together the melted then slightly cooled butter, then whisk in both sugars until well combined.
Whisk in all remaining wet ingredients.
Whisk in the dry ingredients, making sure to spoon and level the flour to measure. Whisk until smooth.
Transfer to you prepared pan and spread evenly.
Bake for 38-34 minutes or until a toothpick comes out clean.
Let cool in the pan for about 15 minutes, then flip onto a wire rack to finish cooling.
Meanwhile, add the butter and cream cheese to a mixing bowl or bowl of a stand mixer and beat with an electric mixer for about 1 minute.
Beat in the powdered sugar, followed by the maple syrup and cinnamon. Add in the heavy cream as needed to reach your desired consistency.
Once the cake has cooled completely, spread the frosting and top. Add some crushed walnuts and banana slices if desired. Slice and enjoy!