How to Make It
In a medium heavy pot over medium low heat, melt the 2 tablespoons of butter, then stir in the sweetened condensed milk, cocoa powder and salt.
Cook the mixture, stirring, until very smooth and slightly thickened, 10 to 12 minutes. Transfer the brigadeiro mixture to a bowl and chill until set, about 30 minutes.
With buttered hands, roll 20 tablespoon-size balls. Roll the balls in the chocolate sprinkles. Chill until ready to serve.