1. In a small saucepan mix the sweetened condensed milk, chocolate, salt, and butter. Heat over medium-low heat.
2. Cook, mixing constantly (being careful not to burn) until it thickens. Proper thickness can be determined by running your spoon or spatula through the middle of the mixture, on end to the other. Once the mixture falls back to fill the space within 5 seconds, the product is done.
3. Remove from heat. Let cool to room temperature.
4. In a plate or bowl, spread your sprinkles. Grease your hands with butter and roll the cooled brigadeiro mixture into little balls, approximately ½ tablespoon big.
5. Roll the balls into the sprinkles and place them in preferred candy cups.