Line a 9"x13" baking pan with foil and butter the foil.
Combine caramel (toasted) sugar, evaporated milk, marshmallows, butter and 1 1/2 teaspoons sea salt in a large sauce pan over medium heat.
5 cup caramel (toasted) sugar, 1 can evaporated milk, 10 ounce mini marshmallows, 1 cup butter, 2 1/2 teaspoon sea salt
Bring to a boil and continue cooking until the mixture reaches 238 degrees F.
Remove the pan from the heat and beat in the chocolate, cream of tartar, vanilla extract and cream cheese using an electric mixer until the mixture is creamy, thick, and starts to hold ridges or trails in the surface for several seconds as you stir.