Line 13x9-inch pan with Reynolds Wrap® Aluminum Foil, with ends of foil extending over sides; spray with cooking spray. Arrange cookies in single layer on bottom of prepared pan.
Microwave caramel bits and milk in microwaveable bowl on HIGH 1-1/2 to 2 min. or until bits are completely melted and mixture is well blended, stirring after each minute. Pour over cookies; spread to completely cover cookies.
Microwave chocolates in microwaveable bowl 2 min. or until almost melted, stirring every 30 sec.; stir until chocolates are completely melted. Pour over caramel layer; spread to completely cover caramel layer.
Let stand 2 hours before cutting into bars.