In a medium saucepan over medium heat, melt the sugar, butter, and milk together. Cook, stirring constantly until the mixture comes to a boil. Boil, stirring constantly, for 1 minute.
Remove the pan from the heat and stir in the chocolate chips and the vanilla extract. Continue stirring until the chocolate has melted and the frosting is soon.
It will be a thin frosting, but will thicken as it cools.
Notes
Nutritional values are approximate and correspond to one tablespoon of frosting. One batch is enough to frost 2 dozen cupcakes or 1 half sheet cake.Pro tip: As the frosting cools, it develops a fudge texture and won't be as easily spreadable. To get it back to spreadable consistency, you can reheat it over low heat with a bit of milk.Feel free to vary the baking chips for whatever flavor you like: dark, semi-sweet, or milk chocolate, white chocolate, butterscotch, cinnamon, espresso, or peanut butterJust a little vanilla helps round out the chocolate flavor. You can also use another extract to flavor the frosting, such as almond, peppermint, or mocha.