Bring the milk and cinnamon stick to a simmer in a thick-bottomed pot over low heat. Allow to gently simmer for 15 minutes, stirring constantly (if you don't stir constantly, the milk on the bottom of the pan will start to cook onto it, and the next time you stir the pot little cooked milk bits will mix into the liquid. Not so fun.) Remove from heat, remove the cinnamon stick, and pour the milk into the serving glass. Add the whiskey and the Frangelico and stir to combine. Top with whipped cream and a sprinkle of cinnamon. Serve immediately.