Put the ground almonds in the water and soak for half an hour. Over a saucepan, drain the soaked almonds through a fine cotton cloth, sqeezing hard to remove all the water.
Mix the cornflour with a little cold water and make a smooth paste, then add this and the sugar to the pan of almond water. Slowly bring to a boil, add the cinnamon, stir for 2 minutes and then turn off the heat. Pour into moulds and let stand for 3-4 hours, until firm.
Serve the puddings with a coating of almond flakes on a platter sprinkled with cinnamon.