Brigadeiros (Brazilian chocolate dessert)

1 (14oz) can sweet condensed milk

4 Tbsp cocoa powder, sifted
2 Tbsp butter, plus more for rolling balls
A pinch of salt 
Good quality chocolate sprinkles (or any other type of sprinkles you like)

1. In a small sauce pan mix the sweet condensed milk, the cocoa powder, the salt and the butter.
2. Bring the sauce pan to the stove and heat it over medium-low heat.
Cook it, mixing constantly (this is important, otherwise it will burn!) until it thickens. 3. A way to know is to run your wooden spoon (or spatula) in the middle of the mixture. If it takes a while for the mixture to move, then your brigadeiro is ready!
4. Reserve, letting it cool to room temperature.
In a plate or bowl, spread your sprinkles.
5. Once the brigadeiro is cool, grease your hands with butter and roll the brigadeiros into little balls.(In Brazil we usually use half a tablespoon as measurement, but you can make your balls as big or small as you'd like!)
6. Roll the brigadeiro balls into the sprinkles and place them in paper/foil candy cups.