Reminiscent of the holiday season’s lights with their multi-colored nonpareils, these treats are also fun to serve any time of the year with some semisweet chocolate shavings on top.
In a medium-sized, heavy-bottomed saucepan, stir together the condensed milk, butter, heavy cream, and corn syrup and bring to a boil over medium heat. Next, add the chocolate and the cocoa powder. Whisk away any lumps of cocoa powder.
Reduce heat to low and continue whisking constantly until it is the consistency of a dense fudgy batter, about 8-10 minutes. (Don't scrape the bottom of the pot too sincerely with the whisk. If the mixture is undercooked, the treats will be too soft; if overcooked, they will be too chewy.)
After 8 minutes, swirl the pan once or twice. The mixture is ready when it slides as 1 piece, leaving a thick residue on the bottom. Slide the mixture into a bowl without scraping the bottom and let cool at room temperature.
Cover the bowl with plastic wrap and chill in the refrigerator for at least 4 hours. Remove from the refrigerator and, using a melon baller or small cookie scoop, measure out 1 generous teaspoon and roll each into a little ball about ¾-inch in diameter between your palms.
Place the sprinkles in a bowl. Roll the ball through the sprinkles, making sure they cover the entire surface. Store in an airtight plastic container for 2 days or up to 1 month in the refrigerator.