Place a small sauce pan over heat and combine condensed milk, brown sugar, butter, and vanilla extract. Stir until mixture is well incorporated and turns a soft brown color. Remove from indirect heat.
Place 4 large marshmallows on Outset Rotating Campfire Fork and place fork in direct heat, close to grill grates but not touching. Rotate to ensure even browning on all sides.
When marshmallows are browned to your liking remove from heat and place on ½ graham cracker. Add a square of dark chocolate, a drizzle of caramel sauce, and a pinch of sea salt. Cover with ½ graham cracker and enjoy!