Pre-heat the oven to 170°C (325ºF) and prepare a large square/rectangle baking tin by lining it with baking paper or by greasing.
Slowly heat the chocolate and butter in a pan until just melted then add in the coffee (or milk)
In a large bowl, whisk sugars together with the eggs, then add in the cooled chocolate mixture.
Sift the vanilla sugar, flour and cocoa and stir into the wet ingredients until just combined.
Pour half of the batter into the prepared pan then splodge over spoonfuls of caramel (it doesn't have to be exact but try to get an even coverage. Top with the remaining batter.
Bake for around 20-22 minutes for a gooey brownie and 25-30 minutes for a firmer one (if you want it to be ultra gooey, keep checking every minute or so from 17 minutes). The brownie's top should be JUST set if baking it gooey (with a wobble) and for a firmer brownie, an inserted skewer will come out clean.
Remove from the oven and either allow it to cool completely or serve it warm with ice-cream. Enjoy!