Brigadeiros and other little sweets made with condensed milk are common birthday or party treats in Brazil. I can never get the consistency for the chocolate ones right, but they still taste good.
Recipe:
1 can sweetened condensed milk
1 large egg
1 tablespoon margarine or butter
3 tablespoons cocoa powder
Method
Put all ingredients into a medium size saucepan and mix well until completely combined and smooth.
Heat on medium, stirring constantly. Initially the mixture will look more liquid than when you started, but eventualy it will start to thicken. When you can see the bottom of the pan for more than just a second when you stir, it’s ready.
Pour onto a dinner plate and spread out to cool. Once cool, put in the fridge for at least an hour, but preferably several, until the mixture has firmed up. I forgot this stage and it made it really hard to roll the balls.
Once the mixture is firmed up, grease your hands with butter or margarine and form little balls. Traditionally, the balls are then rolled in chocolate sprinkles, but I used what I had on hand. Enjoy!
These look delicious! I’ll be right over! 
gears turning lol