Place 6 tablespoons unsalted butter in a large microwave-safe bowl. Microwave on HIGH until just melted, about 40 seconds.

Break 12 full sheets graham crackers and place in the bowl of a food processor fitted with the blade attachment. Process until finely ground, about 30 seconds (about 1 ½ cups).

Add the butter, 2 tablespoons granulated sugar, and ¼ teaspoon kosher salt. Pulse until the mixture looks like wet sand and holds together when pinched between your fingers, 10 to 12 (1-second) pulses. Reserve ¼ cup for garnish.

Transfer the remaining mixture to a standard 9-inch pie pan (not deep dish). Using a flat-bottomed measuring cup, press it evenly into the bottom and about 1 inch up the sides. Refrigerate while you make the fillings.

Place 1 ½ cups mini marshmallows, ¼ cup of the heavy cream, and ¼ teaspoon kosher salt in a large microwave-safe bowl. Microwave on HIGH in 30-second bursts, stirring between each, until the marshmallows are mostly melted, about 1 minute total.

Immediately add 1 cup semi-sweet chocolate chips. Stir until the chocolate is melted and the mixture is smooth. Set aside to cool until barely warm to the touch, 20 to 30 minutes.

Wash and dry the food processor. Place ¾ cup creamy peanut butter, 4 ounces cream cheese, ⅓ cup powdered sugar, 1 tablespoon vanilla extract, and ¼ teaspoon kosher salt in the food processor. Process until well combined, about 1 minute.

Add ¾ cup cold heavy cream and process until smooth and thick, 30 to 45 seconds. Be careful not to overprocess, as it can cause the fat to separate and appear curdled. Transfer ¾ cup to a quart-size zip-top bag or pastry bag fitted with a star pastry tip and reserve for garnish. Transfer the remaining peanut butter filling into the chilled crust and spread into an even layer. Refrigerate while you finish preparing the chocolate filling.

Place the remaining ¾ cup cold heavy cream and 1 tablespoon granulated sugar in a large bowl and whisk until stiff peaks form, about 2 minutes. Transfer ¼ of the whipped cream into the cooled chocolate mixture and stir to lighten the mixture. Add the remaining whipped cream and gently fold just until no streaks of cream remain.

Transfer the chocolate filling over the peanut butter filling and spread into an even layer. Pipe the reserved peanut butter filling decoratively around the border of the pie. Lightly sprinkle the reserved graham cracker crumbs around the edge of the peanut butter border. Refrigerate uncovered until the filling is set, at least 6 hours or up to overnight.