Crockpot Toasted Marshmallow Hot Chocolate + a Hot Chocolate Bar with Dark Hot Chocolate

packages (4 ounces EACH) semi-sweet baking bars (milk or dark chocolate for very rich cocoa, or about 2 and 1/4 cups chocolate chips)

milk (not skim, 1%, 2%, or whole)

and 1/2 cups heavy whipping cream (not whipped)

vanilla extract

salt

sweetened condensed milk

and 1/2 cups miniature marshmallows