Place crushed pretzels in a small bowl; cut in butter until crumbly. Press onto the bottom of a greased 9-inch springform pan. Cover and freeze for at least 30 minutes. Spread fudge topping over crust; cover and freeze.
Set aside 16 chocolate covered pretzels for garnish. Place remaining pretzels in a food processor; cover and process until crumbly. Transfer to a large bowl; stir in ice cream. Spread over the fudge topping. Drizzle with the caramel topping. Garnish with the reserved pretzels. Cover and freeze for at least 8 hours or overnight.