Heat oven to 350°F. Spoon cookie dough in bottom only of greased or sprayed 13x9-inch pan; press evenly in bottom of pan.
Bake 15 minutes. Immediately sprinkle chocolate chips over crust. Let stand 3 to 5 minutes or until chocolate begins to melt. Gently spread chocolate evenly over crust.
Set oven control to broil. Sprinkle peanuts and marshmallows over melted chocolate. Broil with top 5 to 6 inches from heat 20 to 30 seconds or until marshmallows are toasted. (Watch closely; marshmallows will brown quickly.) Cool 30 to 45 minutes to serve warm or cool completely, about 2 hours. For bars, cut into 6 rows by 5 rows, using sharp knife sprayed with cooking spray. Store tightly covered.