CRUST: Combine over hot (not boiling) water, half cup mint-chocolate chips and butter. Stir until chips are melted and mixture is smooth. Add chocolate wafer crumbs; stir until well blended. Press into bottom of 23 cm springform pan; freeze until firm. FILLING: Combine over hot (not boiling) water, remaining 1 cup of chips, corn syrup, and heavy cream. Stir until chips are melted and mixture is smooth. Cool to room temperature. In a large bowl, whip the ice cream until smooth but not melted. Gradually stir in chocolate mixture (flecks will appear in ice cream). Spoon into center of crust, mounding high in center and leaving 2 cm edge. Using spatula, smooth to form dome. Freeze until firm. Remove sides of pan. Preheat oven to 230ºC . MERINGUE: In a large bowl, combine egg whites and cream of tartar; beat until soft peaks form. Gradually add sugar, beat until stiff peaks form. Spread meringue over ice cream and crust to cover completely; swirl to decorate. Bake at 230ºC . for 4 to 6 minutes or until lightly browned. Serve IMMEDIATELY !