Place the condensed milk in a non-stick or thick aluminum pan, sift the chocolate, mix with the condensed milk, add the margarine and bring to a low heat, stirring constantly, when boiling, keep stirring, it will thicken.
When you turn the pan and it's dropping from the bottom, it's at the proper point.
Place on a buttered plate and cover with plastic wrap or place directly on plastic wrap and wrap tightly.
Let it cool completely and you can shape balls, then pass the balls in a chocolate sprinkles or chocolate powder.