Heat oven to 350°F. In ungreased 13x9-inch pan, break up cookie dough. With floured fingers, press dough evenly in pan.
Bake 13 to 16 minutes or until light golden brown.
Immediately sprinkle marshmallows evenly over crust. Sprinkle with half of the cookies. Sprinkle with all of the chocolate chips, peanuts and candy-coated chocolate pieces. Sprinkle with remaining cookies; press lightly into marshmallows.
Bake 4 to 5 minutes longer or until marshmallows begin to puff. Cool completely on cooling rack, about 2 hours. For bars, cut into 6 rows by 6 rows.