1. Preheat the oven to 350°F and line a 9×13-inch baking pan with parchment paper.

2. In a mixing bowl, stir together the brownie mix, eggs, oil, and water until fully combined.

3. Spread the brownie batter evenly into the prepared pan.

4. Bake for 22 to 26 minutes, or until the center is just set and a toothpick comes out with a few moist crumbs.

5. Let the brownies cool completely in the pan.

6. In a bowl, whisk the banana pudding mix with the cold milk for about 2 minutes until it starts to thicken.

7. In a separate bowl, beat the softened cream cheese until smooth.

8. Mix the sweetened condensed milk into the cream cheese until creamy.

9. Fold the prepared banana pudding into the cream cheese mixture.

10. Gently fold in the whipped topping until the filling is light and smooth.

11. Spread the banana pudding mixture evenly over the cooled brownies.

12. Chill for at least 3 hours, or until the topping is firm.

13. Before serving, top with banana slices, vanilla wafer crumbs, and a drizzle of chocolate hazelnut spread or melted chocolate.

14. Slice into squares and serve chilled.