Line the bottom of a 8x8 pan with the crushed up Nilla wafers. This won't make a real solid crust but we are avoiding adding butter to make it real firm. It will really help in getting the pudding out in "pieces" tho.
Use two cups of the milk and make the chocolate pudding to the package directions. Layer this on the Nilla wafer dust and carefully spread.
Top the chocolate pudding with banana slices.
Top the banana slices with half the cool whip.
Make the banana pudding with the last 2 cups of milk to package directions. Layer this on the cool whip.