Preheat the oven to 350°F. Lightly grease a 9" or 10" springform pan., To make the crust: In a large bowl, beat the butter with the confectioners' sugar, salt, vanilla, and cocoa until smooth. Add the flour and pecans and mix until combined., Press the crust evenly into the bottom and 1/2" up the sides of the prepared pan. Bake for 15 minutes, until the bottom has set and you just begin to smell chocolate. Remove from the oven and place on a rack to cool. Reduce the oven temperature to 325°F., When the pan has cooled, crimp some foil around the base where the edges meet the bottom; this will protect against leaks during baking., To make the filling: Place the chopped chocolate in a small bowl; set aside. Combine the cream and corn syrup in a medium saucepan and bring to a boil. Remove from the heat and pour half the mixture over the chocolate., Return the pan to the heat and add the caramel(s). Reduce the heat to low and stir until the caramel has melted. Remove the pan from the heat and set aside. Stir the chocolate mixture until smooth and let both mixtures cool to lukewarm., In a large mixing bowl, stir together the brown sugar, salt, and cocoa until well blended. Add the cream cheese and beat at low speed until the mixture is smooth. Scrape the sides and bottom of the bowl and add the vanilla and then the eggs, one at a time, mixing until each egg is fully incorporated before adding the next., Scrape the bowl, add the melted chocolate mixture, and mix until there are no visible streaks of chocolate in the batter. Pour all but 1/2 cup of the batter over the cooled crust. Add the reserved caramel mixture to the remaining batter and stir to combine. Spoon this mixture over the batter and use a kitchen knife to swirl the two together., Place the springform pan inside a large baking pan (a deep dish pizza pan works well). Place in the oven and pour hot water into the larger pan to a depth of 1". Bake the cheesecake for about 55 minutes, or until the top of the cake is set; the center should still be wobbly. When the temperature of the cake 1" in from the edge reaches 165°F, turn off the oven, prop open the door, and let the cake cool slowly in the turned-off oven for 30 minutes., Remove the cake from the oven and place it on a rack. Carefully run the tip of a thin-bladed spatula between the edge of the cake and the pan; this will help prevent the cake from cracking as it cools. After the cake has cooled for 30 minutes, refrigerate it for at least 6 hours before serving., To make the garnish: Preheat the oven to 350°F. Line a rimmed baking sheet with parchment., In a medium bowl, combine the pecan halves, heavy cream, and brown sugar. Toss until the nuts are evenly coated, then spread them on the prepared pan in a single layer. Bake for 15 to 20 minutes, stirring once, until all the sugar is absorbed and the nuts begin to dry and become crisp., Remove the pan from the oven and place it on a rack. Use two forks to separate any nuts that are stuck together. The nuts will continue to crisp as they cool., Garnish the chilled cake with the praline pecans before serving., Store any leftover cake, well wrapped, in the refrigerator for up to 4 days.