Preheat the oven to 350°F (175°C). Grease and flour a 9×13 inch baking pan.
In a large bowl, combine the yellow cake mix, water, vegetable oil, and eggs. Beat on medium speed for 2 minutes until smooth.
Pour the batter into the prepared baking pan and bake for 30 to 35 minutes or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and allow it to cool completely in the pan on a wire rack.
In a medium bowl, whisk together the instant vanilla pudding mix and cold milk until thickened, about 2 minutes. Refrigerate until ready to use.
In a separate bowl, dissolve the strawberry Jello gelatin in 1 cup boiling water. Stir until completely dissolved, then add 1 cup cold water. Refrigerate until the gelatin is thick but not fully set, about 30 minutes.
In a large mixing bowl, beat the heavy whipping cream, powdered sugar, and vanilla extract together until stiff peaks form. Refrigerate until ready to assemble.
Once the cake is completely cooled, spread the prepared vanilla pudding evenly over the top.
Arrange the sliced bananas evenly over the pudding layer.
Carefully spoon the thickened strawberry Jello over the bananas, spreading gently to cover them completely.
Refrigerate the cake for at least 1 hour to allow the Jello to set.
Before serving, spread the whipped cream evenly over the top of the set Jello layer.
Decorate the top with maraschino cherry halves and chopped walnuts.
Cut into squares and serve chilled.