In large, heavy saucepan combine pudding mix and 3 1/2 cups milk (rather than amount listed in package directions).
Cook over medium heat, stirring constantly, until mixture comes to full boil.
Remove from heat; divide hot mixture between 2 heat-proof medium bowls.
Immediately stir peanut butter chips into mixture in one bowl and chocolate chips into mixture in second bowl.
Stir both mixtures until melted and smooth.
Cool slightly, stirring occasionally.
Alternately spoon peanut butter and chocolate mixtures into parfait glasses, champagne glasses or dessert dishes.
Place plastic wrap directly onto surface of each dessert; refrigerate several hours or overnight.
Top with whipped topping and garnish as desired.