1. Line the bottom of a 9-inch springform pan with parchment paper and lightly grease the sides.

2. In a bowl, stir together the graham cracker crumbs, 1/2 cup melted unsalted butter, and brown sugar until the mixture looks like wet sand and clumps together when pressed.

3. Press the crumb mixture firmly into the bottom of the pan in an even layer using the bottom of a measuring cup. Refrigerate while you prepare the filling.

4. In a large mixing bowl, beat the softened cream cheese until smooth and creamy.

5. Add the powdered sugar and vanilla extract to the cream cheese and beat again until smooth and well combined.

6. In a separate bowl, whip the cold heavy cream to soft peaks, then gently fold it into the cream cheese mixture to keep it light and fluffy.

7. In a microwave-safe bowl, combine 2 1/2 cups mini marshmallows with 1 tablespoon butter and heat in 20-second bursts, stirring between each, until melted and smooth.

8. Quickly stir the melted marshmallow mixture into the cheesecake filling until evenly incorporated.

9. Fold in 3 cups Rice Krispies cereal and the rainbow sprinkles, mixing just until the cereal is coated but still crisp.

10. Spoon the cheesecake mixture over the chilled crust and spread into an even layer, smoothing the top. Refrigerate while you make the topping.

11. In a clean saucepan, melt the remaining 2 tablespoons butter over low heat. Add the remaining 2 1/2 cups mini marshmallows and cook, stirring, until completely melted.

12. Stir in the caramel sauce and a pinch of fine sea salt until the mixture is smooth and glossy.

13. Remove from the heat and quickly fold in the remaining 2 cups Rice Krispies cereal until all the cereal is coated in the caramel mixture.

14. Gently spoon the warm caramel Rice Krispie mixture over the chilled cheesecake layer, pressing lightly to create an even topping without squashing the filling.

15. Cover the pan and refrigerate for at least 4 hours, or until the cheesecake layer is fully set and firm.

16. When ready to serve, run a thin knife around the edge of the pan, release the springform ring, and slice the cheesecake into 10–12 wedges.