Preheat oven to 350°F (175°C). Melt butter, stir in sugar, then add eggs and vanilla.
Sift together flour, cocoa powder, and salt; combine with wet ingredients.
Pour brownie batter into a greased 9-inch springform pan and bake for 25-30 minutes.
In a separate bowl, beat cream cheese, sugar, eggs, vanilla, and sour cream until smooth.
Pour cheesecake mixture over cooled brownie layer; bake for another 30-35 minutes.
For caramel, melt sugar until golden, then stir in butter and cream. Add salt.
Drizzle caramel over cooled cheesecake and refrigerate for at least 2 hours before serving.