In a large mixing bowl, combine the two boxes of instant vanilla pudding mix with 3 1/4 cups of milk. Whisk together until the mixture thickens and is free of lumps. This usually takes about 2 minutes.
In another bowl, pour in 1 cup of heavy cream and sprinkle in 1 1/2 tablespoons of sugar. Use a whisk or an electric mixer to whip the cream until stiff peaks form. This will take about 3-5 minutes.
Gently fold the whipped cream into the pudding mixture. Be careful not to deflate the whipped cream too much; you want to keep it light and airy for that perfect texture.
Slice your bananas thinly just before assembly to avoid browning. Cut each Twinkie into thirds, creating bite-sized pieces that will fit perfectly in your layers.
In a 9x13 inch dish, start with a layer of vanilla wafers at the bottom. Next, add a layer of the pudding mixture, followed by a layer of sliced bananas and a layer of Twinkie pieces. Repeat these layers until all ingredients are used, finishing with a layer of pudding on top.
Cover the dish with plastic wrap and refrigerate for at least 4 hours, or overnight if possible. This allows the flavors to meld beautifully.