Much requested recipe by friends. Based on their preferences of a chewier base, condensed milk caramel, and generous set dark chocolate top, with a touch of salt (but not enough to be a "salted" caramel slice - just add more salt, and scatter with sea salt at the end if you want a proper salted caramel).
Combine all the dry ingredients evenly, then stir through melted butter. Press into lined 18x28cm tin and bake for 15-20 minutes.
Caramel: Place butter, condensed milk and golden syrup in medium saucepan over medium heat. Whisk until mixture begins to thicken (always scrape the pan’s sides and bottom so the mixture thickens evenly and doesn’t stick/burn). Add vanilla bean extract and salt then continue whisking until mixture is thick, heavy and caramel in colour.
Pour over prepared base and bake at 160 degrees C for further 15-20 minutes. Set aside to cool then refrigerate until set.
Chocolate Top: Heat chocolate and butter in heat proof bowl over simmering water until melted (be careful not to get any water or steam in the chocolate or the mix will seize!). Pour/scatter/marble (depending on desired effect) over cooled refrigerated caramel and leave to set.
To Serve: Once set remove the slice from the pan and cut into small slices. Store in airtight container in the fridge (the caramel will soften considerably at room temperature).