For the filling place the sugar into a medium saucepan and melt over medium heat until dark brown in colour, stopping before it starts to smoke. Remove from the heat and carefully pour in the salt and half the cream. The mixture will bubble violently so be careful and go slowly.
Once the mixture has settled add the remaining cream followed by the butter. If the mixture is lumpy place back on the heat and stir until smooth. Pour into a glass jug to cool.
For the brownies preheat the oven to 180°C. Grease a 9x13 light coloured pan and line with a strip of parchment leaving about a 2-inch overhang along the long edges to make removing the brownies easier.
Sift the flour, cocoa powder and salt together into a bowl and set aside.
In a medium pan set over medium heat melt the chocolate and butter together, then remove from the heat and allow to cool slightly. Using an electric whisk or very strong arms whisk the eggs and the sugar until thickened and pale, this is called the ribbon stage. Whisk in the cooled chocolate mixture and then add the flour mixture and fold until just combined, the odd speck of flour showing is fine.
Pour half the batter into the prepared pan and level out with a spatula. Add a thin layer of the caramel, making sure to leave the edges clean (you may not use all the caramel but you can use the excess on ice cream). Add the remaining brownie batter and gently level out. Bake for 25-30 minutes or until a toothpick inserted in the middle comes out with just a few moist crumbs.
Allow to cool in the pan completely before removing and cutting into squares.
Recipe courtesy of Edd Kimber.