• Preheat the oven to 180C. Grease & line a 9 x 9-inch brownie tin with baking parchment; set aside.

for the base

• Place the butter in a saucepan over a medium to high heat & leave to brown. Swirl the butter occasionally. After about 5 minutes, the foam should subside & you should start to see a light brown colour, & it should smell nutty. Remove from the heat & pour into a different bowl to cool to room temperature - or put in the fridge to speed the process up.
• In a large bowl, whisk together the flour and brown sugar. Pour in the cooled butter & mix with a spatula until a dough forms. Neatly press the dough into the prepared tin until evenly dispersed & bake in the preheated oven for about 20-25 minutes, or until lightly golden. Set aside to cool.

for the filling

• While that cools, make the filling. In a medium pot, combine all of the ingredients over a low heat until the sugar has dissolved. Stirring continuously with a whisk, bring the caramel to a high simmer, and cook for 6-8ish minutes, or until the caramel becomes thick and deeply golden brown.
• Remove from the heat, and immediately pour over the base. Use an offset spatula to spread it evenly, and then transfer the pan to the fridge until the caramel is cool to the touch.

for the chocolate topping

• Combine the chocolate and butter in a heatproof bowl set over a pot of simmering water - making sure the bowl doesn't touch the water. Stir with a rubber spatula until melted and homogenous. Leave to cool for 5-minutes.
• Pour the chocolate evenly over the caramel and spread with an offset spatula. Return to the fridge until the chocolate is set.
• Slice into 12, and enjoy!