Chocolate Fudge Frosting

Steps

1. Combine the milk, sugar, butter, corn syrup, and salt in a heavy-bottomed saucepan. Bring to a boil, then wash down the sides of the pot to dissolve sugar crystals.
2. Cook without stirring until the mixture registers 234 °F.
3. Remove from heat. Add chocolate and vanilla extract, but do not stir it in.
4. Place saucepan in a larger pan of cool water, to hasten cooling and minimize crystallization risk. Let cool to 110 °F.
5. Add fondant if using. Beat until mixture just begins to lighten in color and thickens slightly, which indicates sugar crystallization, up to 10 minutes.
6. Spread on cake when still thin enough to flow but thick enough to stay in place, and allow to set.