• Preheat the oven to 350°F and spray three cake pans with nonstick baking spray.

For the Cake:

• Prepare the cake batter following the directions printed on the back of the French vanilla cake mix boxes, combining eggs, water, and oil as instructed.
• Evenly divide the batter among the three prepared pans and bake until a toothpick inserted in the center comes out clean, about 25–30 minutes.
• Remove the cakes from the oven and let them cool completely on a rack. Once cool, level the domed tops with a cake leveler or serrated knife so each layer is flat.

For the Banana Pudding:

• In a large bowl, beat the instant banana pudding mix with the milk until thickened, about 4–6 minutes, until smooth and creamy.
• Stir in the sweetened condensed milk until fully incorporated, then beat in the softened cream cheese until the mixture is silky.
• Gently fold in the Cool Whip until the pudding is light and evenly blended; transfer the filling to a piping bag for easier assembly.

For the Frosting:

• Using a standing mixer, beat the softened butter until creamy. Gradually add powdered sugar, then vanilla and heavy cream, and continue beating until the buttercream is smooth and holds stiff peaks.
• Spoon the finished frosting into a separate piping bag and set aside.

Assembly:

• Place one leveled cake layer on your cake board. Pipe a thick ring of buttercream around the edge to create a barrier that will hold the pudding filling in place.
• Fill the center with the banana pudding from the piping bag, smoothing the top lightly without letting it touch the buttercream rim.
• Set the second cake layer on top and repeat the buttercream barrier and pudding fill. Top with the third layer and spread or pipe the remaining frosting to cover the whole cake.
• Press toasted coconut around the base of the frosted cake to adhere to the buttercream.
• Pour caramel sauce into a squeeze bottle and drizzle it along the top edge so it runs down the sides for a decorative drip effect.
• Pipe even dollops of frosting around the cake top, sprinkle with additional toasted coconut, and press a Nilla wafer into each dollop.
• Refrigerate the finished cake for about 1 hour to firm the frosting before slicing and serving.