In a saucepan, melt the butter over low heat. Once melted, add the marshmallows and stir continuously until they are completely melted and smooth.

Remove from heat and add the Rice Krispies cereal to the melted marshmallow mixture. Stir until all the cereal is evenly coated.

Press the mixture firmly into the bottom of a greased 9-inch springform pan to form an even layer for the crust. Set aside to cool.

In a mixing bowl, beat the softened cream cheese until smooth and creamy using an electric mixer.

Gradually add the granulated sugar, beating until well combined.

Add the vanilla extract, eggs (one at a time), and sour cream, mixing until fully combined and smooth.

Pour the cheesecake filling over the cooled Rice Krispie crust, spreading it evenly.

Preheat the oven to 325°F (160°C) and bake the cheesecake for about 30 minutes, or until the center is set and slightly jiggly.

Once done, remove the cheesecake from the oven and let it cool to room temperature. Then, refrigerate for at least 4 hours or overnight for best results.

Before serving, spread whipped cream over the top of the cheesecake and sprinkle with additional Rice Krispies for garnish.