In a medium saucepan, combine 2 cups of milk, 2 tablespoons of cocoa powder, and 2 tablespoons of brown sugar. Whisk until smooth.

Place the saucepan over medium heat, stirring frequently until it begins to steam, about 5 minutes.

Reduce heat to low and add 1/4 cup of chocolate. Stir until melted and incorporated.

Remove from heat, and stir in 1 teaspoon of vanilla extract and a pinch of sea salt.

Pour into mugs and serve immediately, optionally topping with whipped cream or marshmallows.