Pre-heat the oven to 350 F. Prepare a 9-inch springform pan by covering the bottom and sides with aluminum foil so that it will not leak when placed in a water-bath.
Mix the melted butter into the oreo cookie crumbs so that all the crumbs become moistened.
Press the oreo cookie crumbs into the bottom of the spring form pan and up the sides by at least half an inch. Bake the crust for 5-7 minutes. Remove from oven and allow it to cool.
Pour half of the caramel sauce (recipe below) evenly over the bottom of the crust. Place the pan in the fridge for approximately 15 minutes, or until the caramel sauce has hardened.
Place the cream cheese in a stand mixer or food processor and beat until smooth. Scrape down the sides of the bowl and the beater with a silicon spatula. Repeat frequently to ensure that the batter is uniform and does not form lumps.
Add the sugar to the cream cheese and beat until completely incorporated. Scrape down the sides of the bowl and beater.
Add the eggs one at a time and beat until incorporated, scraping down the bowl and beater after each addition. Add the vanilla and beat until incorporated, once again scrape down the bowl and beater.
Mix in the flour and salt and beat until smooth. Scrape down the bowl and beater.
Fold in the sour cream. Slowly add the melted chocolate with the mixer on low and beat until the batter is uniform and smooth.
Pour the batter on top of the chilled crust and then place the springform pan in a hot water bath. Bake at 350 F for 15 minutes. Turn the oven down to 325 F and bake for an additional hour. Turn off the oven and allow the cheesecake to cool to room temperature. It can be left in the oven overnight. Release the cheesecake from the springform pan.
Warm the remaining caramel sauce and pour over the top of the cheesecake. Garnish as desired. Keep cheesecake in the fridge until ready to be served.
Salted Caramel Pecan Sauce
Spread sugar in an even layer over the bottom of a large saucepan. Place the pan over medium heat.
Once the sugar starts to melt, gently fold the melted sugar from the bottom over top of the unmelted sugar. Keep moving the sugar around and if it is melting too quickly, turn down the heat to avoid burning the sugar.
Continue stirring the melted sugar until it is dark amber and just starting to smoke.
Remove the pan from the heat and stirring in the butter quickly. It will bubble up but keep stirring until the mixture is smooth.
Slowly pour in the heavy cream while stirring. Return the caramel sauce to the heat for a minute and stir until the sauce is uniform.
Carefully, pour the caramel sauce through a strainer to remove any unmelted lumps of sugar.
Stir in the vanilla, salt and pecans.
Reserve the caramel sauce until it is ready to be used. The sauce can be refrigerated for up to two weeks and heated in the microwave to use.