[header] How to make pastillas de leche (candied milk ) [title] Mix the milk and sugar together in a large saucepan on low heat. [step] Mix 5 cups of milk with 2/3 of sugar in the pan, stirring frequently until the sugar is dissolved. You don't have to worry about preheating the pan, it can start cold as the sugar dissolves. 
[title] Cook the mixture, stirring regularly, for an hour. [step] Be sure to scrape the bottom and sides of the pan to prevent burning.