Preheat the oven to 325°F.
Grease a 9-inch springform pan.
In a microwave-safe bowl, melt the butter and marshmallow fluff together.
Stir in the Rice Krispies cereal until fully coated.
Press the mixture into the bottom of the prepared pan to form the crust.
In a large mixing bowl, beat the cream cheese and sugar together until smooth.
Add in the vanilla extract, eggs, and sour cream and mix until well combined.
Pour the cheesecake filling over the Rice Krispie crust.
Bake for 40-45 minutes or until the cheesecake is set.
Remove from the oven and let it cool to room temperature.
Top the cheesecake with mini marshmallows and Rice Krispies cereal.
Drizzle melted chocolate over the top.
Chill the cheesecake in the refrigerator for at least 4 hours before serving.
