Prepare pudding according to package. Allow to cool and thicken.
Begin layering parfaits. Add two Nilla Wafers to the bottom of each cup.
Next, add a layer of vanilla pudding, followed by a layer of Cool Whip, and banana slices.
Repeat with another layer of vanilla pudding and pipe a layer of Cool Whip on top.
Chill parfaits in the fridge while you prepare the Halloween cookie toppers.
In a small pot, melt the white chocolate chips over low heat. Stir until melted completely.
Sandwich a banana slice between two Nilla Wafers. Gently push each cookie together to squish the banana a little bit. That will help it stick to each side of the cookie.
Then, carefully dip the cookie sandwich into the white chocolate. Use a spoon to flip the cookie sandwich in the chocolate. Once fully coated, remove and place on wax paper.
Place the chocolate-covered cookie sandwich in the fridge until hardened.
Meanwhile, melt semi-sweet chocolate over low heat. Stir until melted.
Remove chocolate-covered cookie sandwiches. With a small decorating brush, use semi-sweet chocolate to decorate the chocolate-covered cookie sandwiches with ghost and skeleton faces.
Place cookies back in the fridge to harden.
Sprinkle parfaits with Halloween sprinkles. Then, place a chocolate-covered sandwich cookie on top.
Chill in fridge until serving.