Preheat to 350°F (175°C). Grease or line an 8x8-inch pan with parchment.
Whisk flour, cocoa powder, and salt until smooth.
Beat butter and sugar for 2–3 minutes until pale and fluffy.
Mix in eggs one at a time, then vanilla.
Fold dry ingredients into wet until thick and glossy.
Spread in pan and bake 20–25 minutes, until set but still soft in center.
Cool in pan before adding cheesecake layer.
Beat cream cheese and powdered sugar until smooth, then mix in sour cream.
Spread cheesecake over brownies evenly.
Drizzle caramel on top; swirl if desired.
Refrigerate at least 2 hours before slicing.