Make the salted caramel and set aside to cool and thicken.
Whisk together the melted butter and both sugars. Whisk in the eggs one at a time, then add the flour, cocoa powder and salt and fold together until combined.
Pour half of the brownie batter into the prepared pan. Pour ¾ of the caramel onto the brownie batter. Pour the other half of the brownie batter onto the caramel.
Bake the brownies at 350 degrees Fahrenheit for 35-45 minutes. Let cool completely. Top with the remaining ¼ of caramel. Sprinkle flaky sea salt if desired. Enjoy!