1Heat oven to 350°F. Mix cookie dough as directed on package, using butter and egg. Spread in bottom of ungreased 13x9-inch pan. Bake 12 to 15 minutes or until light golden brown. Cool in pan on cooling rack.
2Meanwhile, in small microwavable bowl, microwave 1 cup of the chocolate chips uncovered on High 1 to 2 minutes, stirring once, until softened and chips can be stirred smooth. In medium bowl, beat cream cheese with electric mixer on medium speed until smooth. Add melted chocolate; stir until blended.
3In small bowl, beat 1 cup of the whipping cream with electric mixer on high speed until stiff peaks form. Fold whipped cream into chocolate-cream cheese mixture until well blended. Spread over cooled cookie base. Cover; refrigerate 1 hour or until set.
4In small microwavable bowl, microwave remaining 1 cup chocolate chips uncovered on High 1 to 2 minutes, stirring once, until softened and chips can be stirred smooth. Stir in remaining 1/2 cup whipping cream until blended. Spoon warm chocolate mixture over mousse layer; spread evenly. Refrigerate 30 minutes or until set. Cut into 9 rows by 4 rows. Store tightly covered in refrigerator.