Special equipment: 4 ovensafe 6-inch skillets
Preheat the oven to 350 degrees F.
In a large bowl, stir together the flour, sugar, cinnamon and salt and set aside. In another bowl, add the buttermilk, baking soda, vanilla and eggs. Mix with a fork and set aside.
In a medium saucepan, melt the butter. Add the cocoa and whisk to combine. Pour the boiling water into the melted butter mixture in the pan. Allow to bubble for a moment, then turn off the heat. Pour the chocolate mixture into the flour mixture. Stir together for a moment to cool the chocolate, then pour in the egg mixture. Stir together until smooth.
Pour the batter into 4 ovensafe 6-inch skillets (unbuttered) and bake until a toothpick inserted in the middle comes out clean, about 20 minutes.
Drizzle the cakes with Cinnamon Hot Fudge Sauce and top with scoops of vanilla ice cream, a dollop of whipped cream and a cherry.
Add the sugar, cream, cocoa, butter and cinnamon to a medium saucepan. Cook over medium heat, stirring, until the butter melts, about 15 minutes. Transfer to a mason jar and store in the fridge. (The sauce will harden as it cools, so reheat in a pan over medium heat when ready to use.)