I got this recipe from Vivi my colleague from Brazil. She made it and it tasted Great!

Condensed milk: 1 can (400 gr)
Cocoa powder (not suggar added): 200 gr aprox.
Butter: 1/2 table spoon

the amount of chocolate depends on how the mix looks like and tastes...

Mix all the ingredients
Cook everything in a pot, low fire, stir until it comes out of the bottom.
Let it cooling down. Make small balls and decorate them with small party candies for cakes.

TIP: grated coconut can be added.