Grease a medium sized bowl. Cook condensed milk, cocoa, and butter in a non stick medium saucepan over low heat, stirring frequently, until mixture is very thick and leaves distinct trail when dragged across bottom of saucepan, around 15-20 minutes.
Pour mixture into prepared bowl and refrigerate until cool, at least 30 minutes or up to 24 hours (cover with plastic wrap if chilling overnight).
Scoop mixture into approximately 1 tablespoon–size pieces and roll into 1-inch balls. Place desired coatings in small bowls and roll each candy in coating until covered. Serve. (Truffle fudge can be refrigerated in airtight container for up to 2 weeks)