Mix together the condensed milk and the cocoa powder until smooth and there are no lumps of cocoa. Note - if your cocoa powder looks lumpy before you use it, sift it into the condensed milk to make a little easier.

Melt the butter in a small pan then add the cocoa-condensed milk and mix in. Cook over a low-medium heat for around 10 minutes, stirring constantly with a wooden spoon, until the mixture thickens enough so that it takes a few seconds to flow back to cover the bottom of the pan when you stir it from the bottom. It will also hold to the spoon pretty well.

Lightly grease a plate with butter then pour the mixture onto the plate. Leave to cool completely (you can speed up in the fridge).

When the mixture is cool, pour some chocolate vermicelli/sprinkles on a small plate and lay out some mini baking cups. Lightly grease the palm and tips of the hand you’ll use to roll with a little butter.

Take a heaped teaspoon of the mixture and roll it in your hand to form a ball. Roll it in the chocolate vermicelli/sprinkles so that it is covered on all sides (you may need to press them on a little) then place in the baking cup. Repeat with the rest of the mixture. They’ll keep a day or two out in a cool place, a good week or more refrigerated.