Grease a medium size baking tray or plate with butter.
In a medium saucepan add butter over low heat.
Once it’s melted, add the condensed milk and the cocoa powder and combine well, turn the heat to medium.
Keep stirring for about 10 -15 mins until you can see a fudgy texture. When you run the spatula through the middle of the pan you should be able to see the bottom of the pan without the mixture running around it.
Remove from heat and pour into the greased plate an let it chill for about 15-20 mins.
Take 1 tbsp of the mixture and form into a small ball.
Coat the balls with chocolate sprinkles or chopped pistachio.