1. Butter a 9 X 13 inch pan (or line with parchment or foil...though I butter my foil too!)
2. Measure out Rice Crispy cereal and set aside.
3. Place marshmallows, peanut butter and vanilla extract in a large, microwave proof bowl. Microwave for 1 minute, remove and stir and continue to microwave until melted and smooth.
4. Add Rice Crispy cereal and gently fold in.
5. Dump into prepared pan and press until flat. (I butter my fingers so it doesn't stick to me.)
6. Peanut Butter Chocolate Ganache: Melt peanut butter and chocolate together in the microwave or over the stove top, stir until smooth. Pour over rice crispy layer.
7. Sprinkle Butterfinger pieces over ganache and let set (about 10 minutes).
8. Remove from pan and use a large knife to slice!