In a medium bowl, combine the crushed Oreo cookie crumbs with melted butter and mix well. Press the mixture firmly into the bottom of a 9-inch square baking dish, ensuring an even layer. Set aside.

Preheat your oven to 325°F (163°C).

In a microwave-safe bowl, heat 1/4 cup of heavy cream with the semisweet chocolate chips in 30-second increments, stirring between intervals until melted and smooth. Set aside to cool slightly.

In a large mixing bowl, use an electric mixer to beat the room temperature cream cheese until smooth and creamy.

Gradually add granulated sugar, cocoa powder, and hot cocoa mix. Mix until combined.

Add the eggs, one at a time, mixing well after each addition.

Pour in the remaining heavy cream, melted chocolate mixture, and vanilla extract. Beat until well incorporated.

Pour the cheesecake filling over the crust, spreading it evenly. Bake for 55-60 minutes or until the edges are set but the center is slightly jiggly.

Remove from the oven and let cool at room temperature for about 30 minutes. Then refrigerate for 2-3 hours, or until fully chilled and set.

While waiting for the cheesecake to chill, whip one cup of heavy cream until soft peaks form.

Gradually add the two tablespoons of hot cocoa mix and continue beating until stiff peaks form.

Spread the whipped cream over the chilled cheesecake, garnishing with a light dusting of cocoa mix and dehydrated mini marshmallows.

Refrigerate for another 15 minutes to set the garnish before slicing into bars and serving.