Preheat your oven to 350°F (175°C) and line your 9x13 baking pan with parchment paper or lightly grease it to ensure easy removal later.
In a large bowl, whisk together unsweetened cocoa powder, granulated sugar, and brown sugar until smooth.
Add the melted butter, eggs, and vanilla extract, stirring until the batter is rich and glossy.
Mix in the all-purpose flour, salt, and optional espresso powder until everything is combined into a thick, decadent batter.
Fold in the chopped dark chocolate for extra gooeyness.
Transfer the batter into your prepared pan, spreading it out evenly.
Bake for 35 to 40 minutes, or until a toothpick inserted comes out with a few moist crumbs. Allow the brownies to cool fully on a wire rack.
While the brownies cool, make the salted caramel: in a medium saucepan, start by melting a small amount of the granulated sugar over medium heat, stirring constantly.
Gradually add the remaining sugar, little by little, ensuring each addition fully melts before adding more. This process helps prevent the sugar from burning and ensures a smooth caramel.
Once all the sugar is melted and golden, add the butter, stirring until fully incorporated.
Slowly pour in the cream and stir continuously until the mixture thickens into a smooth, silky caramel.
Remove from heat and stir in the coarse sea salt.
Once the brownies have cooled and the caramel is ready, pour the caramel over the brownies, spreading it evenly.
Let the caramel set for a few minutes, then slice your brownies into squares. If you like, sprinkle a little more sea salt on top for that perfect finishing touch!
Enjoy while still warm for the best flavor.