Butter 13x9 pan. Melt butter in pan over medium low heat. Stir in marshmallows and stir until melted.Remove from heat and stir in rice krispies. Fold in crushed oreos. Gently press into buttered pan. Melt chocolate chips in microwave in 30 sec intervals until smooth. Spread over treats and sprinkle with remaining oreos before chocolate cools. Press cookies gently into chocolate. Let chocolate harden before cutting.