Mix all the ingredients together in a 6 quart crockpot. Cook on low for 4-6 hours, stirring often the first hour, to make sure the chocolate incorporates and doesn't burn on the bottom.
In the 30 minutes before serving, add large and mini marshmallows to the crockpot. They'll get all melty and yummy! Use a ladle to serve hot chocolate into mugs, then top with all of your favorite hot chocolate toppings.
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Notes
If you don't have a crockpot, you can still make this! You can use this recipe on your stove too!! Place all the ingredients on a large stock pot. Keep on low, stirring often until all the chocolate is melted. Simmer with lid on, stirring occasionally.*You can use 6 cups whole milk, or make it even richer by using 3 cups whole milk and 3 cups half and half. I've done it both ways, and both are yummy! I usually use half and half.