For the caramel:

1. Melt the sugar. Place the sugar in a wide heavy-bottomed frying pan, preferably a steel pan (don’t use a non-stick pan for caramel). Shake the pan to level the sugar. Set the pan over low heat and cook without stirring until most of the sugar has melted, about 30 min. Set the heat to the lowest setting and drag any leftover patches of dry sugar into the hot caramel with a wooden spoon. After 5 to 10 min the caramel should have a dark amber color and be completely smooth. Making caramel can be tricky because it can burn quickly, so always keep an eye on your pan after the sugar has melted.
   

    

2. Add the rest. Add the butter, heavy cream and salt. Be careful as it might vigorously bubble. Let the caramel simmer for 3 to 5 min, stirring often to make sure everything is well combined and melted. When the caramel is smooth again, pour it into a heat-proof bowl and set aside to cool down to room temperature while you get on with the rest of the recipe.
   

For the brownie batter:

1. Melt the chocolate. Roughly chop the chocolate and place in a medium heatproof bowl with the butter. Set the bowl over a saucepan of simmering water (make sure that the bottom of the bowl doesn’t touch the water). Heat until fully melted, stirring occasionally. Then remove the bowl from the pan, set it aside and leave to cool. Butter a 13*18cm (5*7in) baking pan and line it with parchment paper. Set a rack in the middle of the oven and preheat it to 180°C (355°F)*.
   

    

2. Make the batter.  Place the eggs, sugar and salt into a separate large mixing bowl.  Beat together at medium-high speed, using an electric mixer, until pale and the mixture has thickened, about 5 min. Pour in the cooled chocolate mixture and beat at low speed until combined. Sift the flour into the mixing bowl and beat at low speed until just incorporated.
   

    

3. Assemble. Scrape half of the batter into the prepared pan and spread it evenly. I weigh the batter to know exactly how much is a half, otherwise I always end up with 2 uneven layers of brownies (but you don’t have to be this accurate). Drizzle the caramel all over the batter and try to spread it as best as you can without stirring it into the batter. Scrape the other half of the batter on top of the caramel and spread it evenly so that it completely covers the caramel.
   

    

4. Bake. Bake for 35 min. A toothpick inserted in the center should come out with moist crumbs clinging to it. Set the pan over a wire rack and leave the caramel brownies to cool completely before cutting into squares. If you prefer gooey caramel brownies, bake for 25 min, let the pan cool down a bit and then place the caramel brownies in the fridge for 2h.