Remove from heat when the mixture reaches approx. to ones that contained 1/3 cup cornstarch or more (ick!). Cook, covered, on low until potatoes are tender, 6-8 hours. Cool soup slightly. Preheat the oven to 350 degrees F. In a large bowl, stir together the flour, sugar, cinnamon and salt and set aside. Use one of the following methods: Microwave method: Place chocolate and heavy cream in a microwave safe bowl. Transfer to a 4- or 5-qt. Serve with avocado and Cotija cheese. In another bowl, add the buttermilk, baking soda, vanilla and eggs. The chocolate does not need to actually cook at all, just melt completely. Melt the chocolate. Cook in microwave for a minute or so, making sure to stir every 20 seconds. Over a double boiler, heat chocolate with whole milk and stir until smooth. Freeze option: Freeze cooled soup in freezer containers. Process in batches in a blender until smooth. Stir in chocolate until melted. slow cooker. Add broths and sweet potatoes. There are a lot of different chocolate soup recipes out there, ranging from recipes that looked like weak hot chocolate (boooo!)