In a deep saucepan heat over minimum-medium the sweetened condensed milk, unsalted butter, and cocoa powder.
Mix and stir constantly with a wooden spoon until thick. This process takes about 12 minutes and you can’t get distracted because it can burn easily. It’s ready when you stir, and the mixture separates from the saucepan, or you tilt the saucepan and don't stick, it separates.
Pour the mixture into the prepared bowl and let cool at room temperature.
When the mixture is completely cold, roll the balls in the shredded coconut.
Store brigadeiros cover in the fridge.
Notes
Store brigadeiros covered in the fridge for up to 5 days.