In a medium mixing bowl, stir together chocolate wafer crumbs and melted butter. Press onto the bottom of a 9-inch springform pan. Bake in a 350 degree F oven for 10 minutes. Cool slightly on a wire rack.
In a heavy medium saucepan, melt caramels in caramel ice cream topping over low heat, stirring often. Stir in the first 1/4 cup whipping cream. Remove from heat; stir in nuts. Spread over crust. Cool; cover and chill for 1 hour.
For topping:In a heavy small saucepan, melt chocolate. Remove from heat; stir in remaining whipping cream. Drizzle or spread over caramel-pecan mixture. Cover and chill for at least 1 hour. Makes 12 servings.