In a large bowl combine rice krispie cereal, crushed oreos, and 1 1/2 cups crushed graham crackers together. Set aside.
In a large saucepan over medium-low heat, melt marshmallows and 1/4 cup butter together. Remove from heat and whisk in vanilla. Gently fold in cereal mix.
Press into a lightly greased 9X13 inch pan (or 8X8 inch pan for thicker squares).
In a small bowl, melt chocolate chips with a dab of butter or crisco in the microwave, stirring every 10-15 seconds. Drizzle all over the top of rice krispie treats. Sprinkle chocolate with the leftover (1/4 cup) crushed graham crackers.
Notes
**crush the oreos and graham crackers as fine or as chunky as you prefer!