Place 4 ounces finely chopped dark chocolate in a medium, heatproof bowl. Set aside.
Combine 1/4 cup heavy cream and 1 tablespoon unsalted butter in a small, heavy-bottomed sauce pot over medium heat. Bring the cream and butter to a simmer, and pour immediately over the chocolate in the bowl.
Let the mixture stand for 3 minutes, before whisking until smooth. Whisk in 2 tablespoons stout beer until incorporated.
Immediately transfer to your serving bowls of choice and sprinkle the the tops of each bowl with flaky sea salt. Serve immediately with your dippers of choice, and enjoy!