Heat oven to 450°F. Make pie crust as directed on box for One-Crust Baked Shell using 9-inch glass pie plate. Before baking, sprinkle chopped pecans over bottom of crust; lightly press into crust. Bake 9 to 11 minutes or until lightly browned. Cool completely, about 15 minutes.
Meanwhile, in large bowl, place chocolate. In 2-quart saucepan, heat 2 cups of the whipping cream over medium heat just until it begins to boil. Pour over chocolate. With electric mixer on low speed, beat 1 minute or until chocolate mixture is smooth. Pour into cooled baked shell. Refrigerate at least 4 hours or until serving time.
Just before serving, in small bowl, beat remaining 1/2 cup whipping cream with electric mixer on high speed until stiff peaks form. Spoon or pipe whipped cream around outer edge of pie. Top each serving with pecan half.