Heat the milk, bittersweet chocolate, butter and salt in a heavy saucepan over medium heat until the mixture thickens, about 15 minutes. Make sure you keep mixing the pan constantly with a wooden spoon. When the mixture begins to "dis-glue" from the pan or when you can see the bottom of the pan after scraping the wooden spoon on the bottom of the pan, you know the cooking process is over.
Remove from heat and transfer mixture on a well greased plate.
Let cool for 15 minutes.
Grease your hands well and form 1 inch balls with your hands. Roll the balls into a plate full of sprinkles. Cover the ball well with the sprinkles. You may need to wash your hands in between rolling out these candies, because after a while the mixture will begin clinging to your hands. Wash out your hands, grease them up again (I just use a spray bottle) and begin rolling again. Serve in miniature paper liners.