First, make your rosemary salted caramel. Put the cream and rosemary in a small pan over low heat. Once the cream comes to a simmer, turn the heat off and set the pan aside for 20 minutes for the rosemary to infuse into the cream. Strain the rosemary from the cream to use in step 4.
In a medium saucepan, heat the sugar over medium-high and occasionally stir. The sugar will begin to clump up, and eventually turn a lovely brown colour and fully melt after about 5 minutes.
Once the sugar is amber coloured, remove it from the heat and stir in the butter for about 2 minutes until fully combined. The mixture will bubble when you add the butter but don’t be afraid!
Add the rosemary cream and salt and place the pan back on the medium-high heat and stir for another 30-60 seconds until mixture is smooth and well combined. Set the caramel aside to cool while you make the batter and set your oven to 180c/160 fan.
Melt the butter and 60g chocolate in a microwave safe bowl. Melt in small increments of 30 seconds, stirring the mixture each time until the ingredients are fully melted. Alternatively, do this in a small pan in the stove but take care to ensure the mixture doesn't burn. Move the mixture to a larger bowl if needed.
Whisk in the sugar into the butter and chocolate mixture until fully combined, followed by the eggs and vanilla.
Add the flour, cocoa powder, salt, and remaining chopped chocolate. Fold the ingredients together until combined and you have a thick batter.
Line an 8x8 metal pan with parchment and spread 3/4 of the batter into the pan before pouring 3/4 of the caramel evenly across the first layer. Spread the remaining brownie batter before drizzling the top with the caramel. You can also marble the caramel with a knife.
Bake in the oven for about 45 minutes until a toothpick comes out with very few crumbs.
Remove the brownies from the oven and allow the brownies to cool slightly before adding sprigs of rosemary for garnish and sprinkling with sea salt (optional). Allow the brownies to cool fully before cutting and serving.