Adapted from this recipe on About.com. Makes 14 1-1/4 inch bonbons.
1 14-oz can sweetened condensed milk
4 Tbsp cocoa powder (I used Ghirardelli ground chocolate; you can also use Nesquick.)
1/4 tsp kosher salt
3 Tbsp butter
1 tsp pure vanilla extract
Chocolate and/or multicolored sprinkles for decoration
Pour the condensed milk into a heavy straight-sided, deep 2-quart sauce pan. Stir in the cocoa powder and salt.
Cook, stirring constantly, over low heat. Keep the mixture barely at a boil to prevent burning and sticking.
Cook for 10-15 minutes, stirring, until mixture becomes very thick and shiny and starts to pull away from the bottom and sides of the pan.
Remove from heat and vigorougly stir in the butter and the vanilla, until the mixture is smooth and all of the ingredients are incorporated..
Chill in the refrigerator for 30 to 60 minutes. With buttered hands, roll the mixture into one-inch balls, or use a cookie scoop with a quick release (called a disher).
Roll each ball in the sprinkles, pressing lightly to ensure that the sprinkles adhere, and place in a paper liner.
Chill until ready to serve. Can be made hours, or even days, ahead.