Preheat the oven to 350°F (175°C). Grease and flour a 9×13-inch baking pan.
In a large bowl, combine the banana-flavored cake mix, water, vegetable oil, and eggs. Beat with an electric mixer on medium speed for 2 minutes.
Pour the batter into the prepared baking pan and bake for 22 to 25 minutes or until a toothpick inserted in the center comes out clean.
Remove the cake from the oven and allow it to cool completely in the pan on a wire rack.
While the cake is cooling, prepare the strawberry gelatin. In a medium bowl, dissolve the strawberry gelatin powder in 1 cup of boiling water. Stir until completely dissolved.
Add 1 cup of cold water to the gelatin mixture and stir. Refrigerate until the gelatin is partially set but still pourable, about 45 minutes to 1 hour.
Once the cake is completely cooled, use a fork or skewer to poke holes all over the surface of the cake.
Slowly pour the partially set strawberry gelatin over the cake, allowing it to seep into the holes. Refrigerate the cake for at least 1 hour to fully set the gelatin.
In a medium bowl, whisk together the instant vanilla pudding mix and cold milk. Let it set for 5 minutes until thickened.
Spread the vanilla pudding evenly over the gelatin layer on the cake.
Arrange the sliced bananas evenly over the pudding layer.
Spread the thawed whipped topping over the bananas, smoothing it out with a spatula.
Sprinkle the chopped pineapple, chopped maraschino cherries, and chopped nuts (if using) evenly over the whipped topping.
Refrigerate the cake for at least 1 hour before serving to allow all layers to set and flavors to meld.
Cut into squares and serve chilled.