Set the oven to 300 degrees and line a cookie sheet with aluminum foil.
Place the graham crackers in a large sealable plastic bag and smoosh with a rolling pin until most of it is pulverized, or pulse in a food processor for just a few seconds before you end up with a coarse sand-like quality.
Mix the graham cracker in a bowl with the melted butter and ¼ cup of sugar. Spread out on the cookie sheet and put in the oven for 10 minutes. Remove from the oven, stir and let cool on the cookie sheet.
Make the pudding as directed on the package and chill. (This usually means mixing the pudding mix with the milk).
Pour the cream, ¼ cup sugar and vanilla into a large bowl and mix until you have whipped cream (about 3 minutes).
To assemble, line a bowl with the Vanilla wafers, flat side down. Spread in one-third of the pudding. Place a layer of the sliced bananas on top of the pudding. Top with one-third of the whipped cream. Drizzle the sundae topping onto the whipped cream and then sprinkle half of the graham cracker bits on top of that.
Repeat the layers one more time with the rest of the ingredients, adding Nilla wafers to the side of the bowl as you go.
Cover in saran/plastic wrap and chill for an hour before serving.