Line the pan: Line a 9x13-inch baking dish with parchment paper, leaving extra paper over the sides for easy lifting.
Add graham crackers: Arrange half of the graham crackers in a single layer on the bottom of the pan, trimming pieces if needed.
Make chocolate layer: Whisk pudding mix with cold milk until smooth and slightly thickened. Fold in 1/2 cup whipped topping, then spread over the crackers.
Chill briefly: Place the pan in the freezer for 10–15 minutes to help the chocolate layer set.
Make marshmallow layer: Beat softened cream cheese until smooth. Add marshmallow creme, then fold in remaining whipped topping and salt.
Spread filling: Spread the marshmallow mixture evenly over the chocolate layer, smoothing it gently into the corners.
Top and freeze: Add the remaining graham crackers on top, cover the pan, and freeze for at least 6 hours or overnight.
Slice and serve: Lift the frozen slab from the pan, cut along the graham cracker lines, and let the bars soften for 10–15 minutes before serving.
