In a medium bowl, combine cookie crumbs and butter. Mix well.
Press mixture into a pie plate.
Pour hot fudge over crust. Smooth to cover.
Place in the freezer for 1 hour or more (can be down ahead of time).
In a large bowl, add cream cheese and powdered sugar. Beat with an electric mixer until fully mixed.
Mix in peanut butter and vanilla. Beat until smooth.
Beat in about 1 cup of the Cool Whip.
Add the remaining Cool Whip and fold in using a rubber spatula - do not use the electric mixer. Keep folding until the mixture is well combined.
Spoon peanut butter filling into the frozen pie crust. Smooth the top.
Place pie back into the freezer. Freeze for at least 3 hours, or until set enough to slice easily.
Drizzle additional hot fudge on individual slices, if desired.