Preheat the oven to 350°F. Spray a 9x13-inch baking dish with nonstick spray.
In a large bowl, whisk together 1 3/4 cups skim milk and 1 box (3.4 oz) instant banana cream pudding mix until fully combined and slightly thickened.
Add 1 box (15.25 oz) white cake mix to the pudding mixture. Stir with a large spoon or spatula until the dry cake mix is fully incorporated and the mixture is smooth and very thick.
Stir 1/2 cup milk chocolate chips into the cake-pudding mixture. Set this mixture aside.
In another large bowl, combine 1 cup chopped fresh strawberries, 2 sliced bananas, 1 cup chopped pineapple, and 1/4 cup sugar. Stir to combine, then let the fruit sit (macerate) for at least 5 minutes so it releases some juices.
Pour the macerated fruit and any juices into the prepared 9x13-inch baking dish and spread into an even, thin layer.
Spoon the thick cake-pudding mixture over the fruit and spread it into an even layer using a spatula or the back of a spoon.
Bake in the preheated 350°F oven for 45–60 minutes, or until the top is set and a toothpick inserted into the center comes out clean.
Remove from the oven and let the cake rest for about 10 minutes before serving. Serve warm, topped with whipped cream if desired.