Line the bottom of a deep 6-inch springform pan with plastic wrap to prevent sticking.

In a mixing bowl, combine crushed graham crackers, brown sugar, melted unsalted butter, and ground cinnamon. Press half of this mixture firmly into the base of the pan, forming a solid crust.

Set the remaining crust mixture aside for topping later.

In a heatproof bowl, combine semi-sweet chocolate chips and corn syrup. Pour hot heavy cream over the mixture, letting it sit for 2–3 minutes before stirring until smooth and glossy.

Spread half of the fudge sauce over the prepared crust. Place the pan in the freezer for 30 minutes to set the sauce.

Preheat your broiler. Spread regular marshmallows evenly on a baking sheet and broil for 1–2 minutes, or until golden brown. Watch closely to prevent burning.

Once toasted, remove from the oven and let them cool slightly.

In a blender, combine the toasted marshmallows with half of the sweetened condensed milk. Blend until smooth and creamy. Set aside.

Melt the milk chocolate in a microwave-safe bowl in 30-second intervals, stirring until smooth. Stir in the remaining sweetened condensed milk and unsweetened cocoa powder until well mixed.

In a separate bowl, whip heavy cream to stiff peaks. Gently fold half of it into the toasted marshmallow mixture.

Repeat this process with the remaining whipped cream into the chocolate mixture.

Spread the marshmallow ice cream layer over the chilled fudge sauce, smoothing it out evenly.

Sprinkle the reserved graham cracker crust mixture on top of the marshmallow, then pour the remaining fudge sauce over it.

Cover the pan with plastic wrap and freeze for at least 4 hours.

Pour the chocolate ice cream mixture into a lined pan and freeze alongside for approximately 4 hours, or until solid.

Once fully frozen, stack the chocolate layer on top of the marshmallow layer on a serving plate.

Coat the sides with chocolate whipped cream frosting for a smooth finish, and freeze briefly for 20-30 minutes.

Apply a final layer of frosting and garnish with toasted mini marshmallows, chocolate pieces, and crushed graham crackers.

Return the cake to the freezer until you’re ready to slice and serve.