Preheat oven to 350°F (175°C). Grease and flour a 9-inch springform pan.
In a saucepan, melt butter. Remove from heat and stir in sugar and cocoa powder until well combined. Beat in eggs one at a time, then stir in vanilla.
Gradually add flour and salt to the butter mixture, mixing until just combined. Pour into the prepared pan.
In a large bowl, beat cream cheese and sugar until smooth. Beat in eggs one at a time, then stir in sour cream and vanilla. Pour over the brownie layer.
Bake for 45-50 minutes, or until the center is almost set. Let cool completely in the pan before refrigerating for at least 4 hours.
Before serving, drizzle with caramel sauce and sprinkle with chopped pecans, if desired.
Serve chilled and enjoy!
Notes
For a richer flavor, use dark chocolate cocoa powder. You can also add chocolate chips to the brownie layer.