1. In a medium saucepan over low heat melt the butter, add sweetened condensed milk, cocoa powder and salt. Cook, stirring constantly, until the mixture becomes very thick and starts to pull away from the bottom and sides of the pan. About 6-8 minutes. Do not overcook. 2. Remove from heat and pour into greased plate or pan. Let cool for 1 hour. 3. grease your hands with butter and shape into small balls. Then, roll in topping of your choice. 4. Keep refrigerated before serving.