Place the graham cracker crust in the freezer for 15 minutes while preparing the filling to prevent sogginess.
In a large mixing bowl, beat the softened cream cheese and peanut butter together with an electric mixer on medium speed until completely smooth, about 2 minutes. Scrape down the sides of the bowl.
Add the powdered sugar and 1/4 cup of the caramel sauce to the cream cheese mixture. Beat until fluffy and well combined, about 1 minute.
Gently fold in the thawed whipped topping using a rubber spatula with broad, sweeping motions from bottom to top. Don't overmix or the filling will deflate.
Reserve about 1/2 cup of the chopped Snickers bars for topping, then fold the remaining chopped candy into the filling mixture until evenly distributed.
Spread 2 tablespoons of caramel sauce over the bottom of the chilled crust. Spoon the filling on top and smooth with an offset spatula.
Top with the reserved Snickers pieces and chopped peanuts if using. Drizzle with remaining caramel sauce and chocolate syrup.
Cover loosely with plastic wrap and refrigerate for at least 4 hours or overnight before slicing. Let stand 10 minutes at room temperature before serving.