Preheat the oven to 325°F. Spray a 9-inch springform pan with nonstick cooking spray.

In a large bowl, combine the butter, sugar, cocoa powder, and salt. Stir until well combined. Let cool to just warm if the butter is still hot. Stir in the vanilla and then the eggs, one at a time, stirring very well after each addition. Stir until the batter is very well blended. Add the flour and stir again until combined. Spread into prepared pan.

Bake for 15 minutes, or until just starting to set but not fully cooked. Let cool to room temperature then place in the fridge to chill until ready to use.

In the bowl of an electric mixer, beat the cream cheese until smooth, about 1 minute. Add the sugars and cream and beat until well combined. Scrape down the sides and bottom of the bowl to ensure all cream cheese is incorporated. Add the eggs, one at a time, beating just until smooth. Add in the vanilla.

Pour the batter on top of the cooled brownie crust and tap the pan to remove any air bubbles. Place the springform pan on a rimmed baking sheet and bake for about 55 minutes to 1 hour, or until the top looks slightly dry. If the middle is slightly wobbly, that's fine.

Turn off the oven, crack the door open, and allow to cool for 10 minutes to prevent cracking. Remove the cheesecake from the oven to a wire rack to cool completely to room temperature.

Refrigerate until completely chilled, at least 4 hours or overnight.

Release the cheesecake from the pan onto a cake stand or serving plate. Cut into slices and drizzle each slice with caramel sauce. Serve.