Start by making the pudding component. Pour 1 1/2 cups of cold whole milk into a large mixing bowl. Add the instant banana pudding mix and whisk vigorously for about 2 minutes until the mixture is thick and no lumps remain. Set aside for 5 minutes to thicken to a pudding consistency.

In a separate bowl, pour in 1 cup of cold heavy whipping cream and beat on medium-high speed until soft peaks form (about 2-3 minutes). Add 1/2 cup powdered sugar and 1 teaspoon vanilla, continuing to beat until firm peaks form. Set aside.

In a large mixing bowl, add 16 oz of softened mascarpone cheese and beat on medium speed for about 1 minute until smooth and creamy. Add the banana pudding mixture and blend on low until combined. Gently fold in the whipped cream using a rubber spatula.

Pour 1/2 cup of milk (or syrup) into a shallow bowl. Dip each vanilla wafer for about 2-3 seconds per side, ensuring they are lightly moistened but not soggy.

In a 9x13 inch dish, spread a thin layer of mascarpone cream to coat the base. Add a layer of dipped wafers tightly packed, then spread half of the mascarpone filling over the wafers. Lay half of the banana slices evenly on top. Repeat the process with another layer of dipped wafers, remaining mascarpone cream, and the rest of the bananas.

Whip the remaining 1/2 cup heavy cream with 2 tablespoons of powdered sugar and 1 teaspoon of vanilla until firm peaks form. Spread or pipe this over the top layer then sprinkle with crushed vanilla wafers. Cover tightly with plastic wrap and refrigerate for at least 4 hours, preferably overnight.