1Heat oven to 425°F. Grease 9-inch glass pie plate with shortening or cooking spray. In medium bowl, place Bisquick mix. Cut in butter with pastry blender or fork (or pulling 2 table knives through mixture in opposite directions) until mixture looks like fine crumbs. Stir in water; shape into ball with hands. Press dough in bottom and up side of pie plate.
2Bake 10 to 12 minutes or until lightly browned. Cool completely, about 30 minutes.
3Meanwhile, in 2-quart saucepan, mix granulated sugar and cornstarch. Gradually stir in milk; cook over medium heat until mixture boils, stirring constantly. Reserve 1 tablespoon chocolate chips for topping; coarsely chop. Add remaining chocolate chips and vanilla, stirring until melted and smooth. Pour into medium bowl; cover surface with plastic wrap. Refrigerate about 30 minutes to chill.
4In large bowl, beat whipping cream and powdered sugar with electric mixer on high speed until stiff peaks form. Reserve 1 cup for topping. Beat cooled chocolate mixture with electric mixer on medium speed about 2 minutes or until smooth and creamy; fold into whipped cream in large bowl. Spoon evenly into cooled baked crust. Pipe reserved whipped cream around edge of pie; sprinkle with reserved chopped chocolate chips. Refrigerate 6 to 8 hours or until set before serving. Cover and refrigerate any remaining pie.