In a large pot, boil the rice for 10 minutes. Add 3 ½ cups of milk and let simmer for 15 minutes while stirring continuously. Add the sugar to the pot. In a small bowl, mix the corn flour with the rest of the milk and pour this into the pot. Boil the “ryzogalo” mixture for 10-15 minutes more stirring continuously, until it starts to thicken. Finally remove it from the fire and add the vanilla while continuing to stir. Let cool or refrigerate for 20 minutes. Serve in small bowls and garnish with cinnamon.