In a small sauce pan over medium-high heat, combine the sweetened condensed milk, bittersweet chocolate, cocoa powder and salt. Bring to a low boil, stirring constantly with a large heatproof spoon. Reduce heat to medium-low and cook for approximately 10 to 15 minutes, until mixture is shiny and thick and pulls away from the bottom of the pan (you might have to tilt it a bit to see this), taking care to stir constantly. Do not overcook the mixture or it will become too chewy. These are suppose to be mix between fudge and a soft caramel.
Remove from the heat and stir in the cream, butter and vanilla until melted and smooth. Pour the mixture into a dish or bowl and cover. Refrigerate for 2 hours or until firm.
Once the mixture is set remove from the refrigerator and allow to sit at room temperature for 5 minutes. Using a half tablespoon, scoop balls (you may have to smooth or round them out in the palms of your hands) and roll into the sprinkles, covering them completely. Serve immediately or place in an airtight container and refrigerate for 2-3 days.
*I used a half of a 4 oz. Ghirardelli baking bar. -Chocolate jimmies are usually used to roll the chocolate caramels in, however since it's World Cup, I went with colorful jimmies. Also cocoa powder or finely chopped nuts can be used too.