Mix together Rice Krispie and crushed Oreo, then set aside. Lightly grease a pan or place a parchment paper in it.
Melt the butter in saucepan over medium heat and add the marshmallow while turning the heat to lowest setting. Continue stirring until all marshmallow melt.
Once they melted, pour it over the Rice Krispie mixture. Stir until all combine.
Pour the Rice Krispie mixture to the pan (i used parchment paper). Press it down and allow to cool completely before cutting it.
I drizzle mine with white chocolate