In a bowl set over simmering water (or on 50% power in microwave), melt the chocolate, removing from the heat and adding the sour cream and salt.
Line a 8×8 pan with parchment paper; grease or spray.
Lay down 1/2 the graham crackers, marshmallows, and pretzels.
Pour the chocolate on top of the graham cracker mixture.
Top with remaining graham crackers, marshmallows, and pretzels.
Freeze until set; cut into 16 squares. Serve!