Melt first 3 ingredients in a heavy saucepan over low heat, stirring occasionally until smooth. Remove from heat; cool.
Beat chocolate mixture and sugar at medium speed with an electric mixer until blended. Add eggs and vanilla, beating until smooth. Add flour and next 3 ingredients, beating until blended. Stir in pecans. Pour into a lightly greased 9-inch pieplate.
Bake at 325° for 40 minutes. Remove from oven; cool completely on wire rack.
Press down center of crust gently. Spread ice cream over crust. Cover and freeze 8 hours.
Beat whipping cream and powdered sugar at medium speed with electric mixer until soft peaks form. Spread over ice cream. Sprinkle with crushed candy.
NOTE: For testing purposes only, we used Ovaltine Chocolate Malt Mix.