Stir together sweetened condensed milk, egg yellow, unsweetened cocoa, chocolate and butter over medium-low heat until you can create a ditch in the bottom of the pan when you run the spoon through the center of the mixture. It should stay apart for a second or two.

Stir gently to keep from scorching. It should look like a thick paste.

Let it cool off just long enough for you to be able to touch it.

Oil your hands with vegetable oil a little so you don't make an unholy mess.

Shape into tiny spheres and roll them in the granulated chocolate. 

Put them into tiny cupcake holders .