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.
Meanwhile, 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.
In 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.
In 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.