Melt the butter in a heavy saucepan over low heat.
Add Cadbury Cocoa Powder; stir until smooth.
Add sweetened condensed milk; increase heat to medium. Cook, and stir constantly for about 4 minutes or until mixture is smooth and glossy with a pudding-like consistency.
Remove from heat; stir. Cover; refrigerate for 3 to 4 hours or until firm.
Shape into 1-1/4-inch balls; roll in Cadbury Cocoa Powder or powdered sugar.
Refrigerate until firm, 1 to 2 hours. Cover it and store in the refrigerator.