In a medium saucepan, melt the butter over low heat. Add the mini marshmallows and stir until completely melted and smooth. Remove from heat.
In a large mixing bowl, combine the melted marshmallow mixture with the Rice Krispies cereal. Mix until the cereal is evenly coated with the marshmallow.
Press the Rice Krispie mixture firmly into the bottom of a 9-inch springform pan to create an even crust. Set aside to cool and firm up.
In another large bowl, beat the softened cream cheese with an electric mixer until smooth. Gradually add the powdered sugar and vanilla extract, mixing until well combined.
In a separate bowl, whip the heavy cream until stiff peaks form. Gently fold the whipped cream into the cream cheese mixture until combined, being careful not to deflate the cream.
Pour the cheesecake filling over the cooled Rice Krispie crust. Spread it evenly with a spatula.
Refrigerate the cheesecake for at least 4 hours or until set, preferably overnight.
Once set, remove the cheesecake from the springform pan and garnish with chocolate chips if desired. Slice into 12 equal servings.