By hand or using an electric mixer on low speed, beat together the peanut butter, cream cheese and sugar. Fold in 3 cups of the whipped topping. Spoon mixture into the pie shell and smooth the top.
Set aside 2 tablespoons of the hot fudge sauce, then carefully spread it over the peanut butter mixture. If the fudge sauce is room temperature you shouldn't need to soften it, but if for some reason it seems too thick to spread, soften it.
Cover and chill for 4 hours or until ready to serve.
Just before serving spread or pipe remaining whipped topping over fudge layer.
Place the reserved 2 tbsp. hot fudge in a freezer bag, then cut a tiny hole in the corner of the bag and drizzle over the pie.
Place 2 tablespoons of peanut butter in a zipper bag, soften in the microwave for about 2 seconds, then snip a hole in the corner and drizzle peanut butter over.