Preheat the oven to 350°C. Line the bottom of the springform pan with parchment paper.

Melt the butter, then add the Oreo crumbs, salt, and sugar. Mix well. The mixture should have the consistency of wet sands.

Pour the mixture at the bottom of the pan, and press down with the bottom of a glass or a measuring cup. Bring the crust up to the sides about ½ inch.

Bake this in the oven for 10 minutes.

Reduce the oven temperature to 325°C.

Melt the chocolate on double boiler and let cool slightly.

With the stand mixer on the whisk attachment, cream the cream cheese and the sugar until smooth. Add the flour, salt, and vanilla extract, and mix well.

Add the eggs, one at a time, and beat after each addition. Add the melted chocolate and mix.

Pour this mixture over the baked crust. Place the springform pan in a dry brownie pan and place the brownie pan inside a larger pan. Fill up the second pan up to ⅔ of the brownie pan with boiling water. Water should not touch the cheesecake.

Bake for one hour. DO NOT OPEN THE OVEN. After one hour test to see if the sides are set. Gently shake the pan. The sides should be firm, but the center will jiggle. Turn the oven off and leave the cheesecake in the oven for two hours. Crack open the oven and let the cheesecake sit in the oven for another hour. Let sit in the fridge for 2 hours before serving.

Pour the ganache over the cheesecake and cover the top with mini Oreos.

Heat the heavy cream in the microwave, at 30-sec intervals. Cream starts to simmer from the sides, and should not boil.

Remove from microwave and add the chocolate and the rum if using. Let the chocolate sit in the warm cream for a few minutes. Then stir until all the chocolate is melted and the mixture becomes smooth.