1. Melt butter in heavy saucepan over low heat; add cocoa, then 2/3 cup sweetened condensed milk, stirring until smooth and slightly thickened. Pour mixture into medium bowl; cool to room temperature. Beat in 1 tablespoon orange juice and 1 teaspoon orange peel.
2. Beat whipping cream in large bowl until stiff. Fold half of whipped cream into chocolate mixture. In second medium bowl, stir together remaining sweetened condensed milk, remaining 1 tablespoon orange juice and 1 teaspoon orange peel. Fold in remaining whipped cream.
3. Spoon equal portions of chocolate mixture into 8 dessert dishes, making a depression in center of each. Spoon creamy orange mixture into center of each. Refrigerate until well chilled. Garnish as desired. Refrigerate leftover dessert. 8 servings.