1. Crush the nilla wafers into a fine crumb.
2. Mix the nilla wafer crumbs with the melted butter.
3. Press into the bottom of a greased 9 or 10 inch pie pan. Press the crumbs up the sides as much as it will go. Set in the freezer while you make the filling.
1. Mix cake mix and 6 tbsp of milk together. It will be thick.
2. Mix the cream cheese, milk, cake mix mixture and sugar together with an electric mixer. Mix until smooth.
3. Gently fold in Cool Whip.
4. Remove pie crust from freezer and add half of the pie filling into the crust.
5. Add a layer of rainbow chip icing.
6. Add the remaining pie filling.
7. Heat about 1/4 cup rainbow chip icing for about 5-7 seconds, until pourable.
8. Pour rainbow chip icing over top of pie and add sprinkles.
9. Freeze overnight.