To make the caramel, line an 8x8 baking dish with parchment paper.

In a large pot, cook the sugar over medium heat, stirring constantly with a heat proof rubber spatula until the sugar has melted and turns a golden caramel, about 8 minutes.

Remove the pot from the heat and add the chunks of butter, whisking until combined.

The caramel will bubble and begin to harden, just keep stirring and slowly add the cream and then whisk until combined.

Return the pot to medium heat and cook the mixture, stirring until the caramel has thickened, about 5 minutes.

Remove from the heat and stir in a pinch of salt and the vanilla.

Pour into the prepared pan and transfer to the freezer to harden for 20-30 minutes.

Cut the caramel into ½ inch squares.

Meanwhile, make the brownies by preheating the oven to 350 degrees F and lining a 9x13 inch baking dish with parchment paper.

Add the butter and chocolate to a medium microwave safe mixing bowl and microwave on 30 second intervals, stirring after each interval, until melted and smooth.

To the melted chocolate, whisk in the sugar, instant coffee, vanilla, hazelnut liquor (if using), and eggs until smooth.

Stir in the cocoa powder, flour, and salt until just combined, being careful not to over mix.

Pour half the batter into the prepared pan, spreading it in an even layer.

Arrange half of the caramel squares over the brownie batter.

Spread the remaining brownie batter over the caramels.

Transfer to the oven and bake for 25-30 minutes, until the brownies are set on top.

Remove from the oven and allow to cool completely before cutting, at least 30 minutes.

Sprinkle with sea salt before serving.