Peel the rind of one lemon. Pour the milk, sugar, lemon rind and cinnamon sticks into a pot and bring it to a boil. Watch it carefully, so that it does not boil over and burn. Once it begins to boil, lower the flame and allow it to simmer, covered if possible, for 10 minutes. The milk will acquire the delicate taste of the cinnamon and lemon, and you will want to drink it all, but don’t do it! You need it for the torrijas.