Perfect Fudge Frosting
- Clip a candy thermometer to a 3-qt. saucepan.* Combine chocolate, sugar, milk, corn syrup, and salt in the saucepan. Heat and stir over medium heat to dissolve sugar. Bring to boiling over medium-high heat, stirring constantly. Reduce heat to medium, maintaining a moderate steady boil until mixture reaches 232 degrees F, 6 to 8 minutes, stirring occasionally (keep a very close eye on the temperature at this point). Carefully remove saucepan from heat and place on wire rack or pot holder. Add butter (do not stir or disturb mixture). Cool until 110 degrees F, about 1 hour. Add vanilla. Beat with a mixer on low until frosting thickens and lightens in color, about 20 minutes (the mixture will have the consistency of a glaze initially but will set up nicely as it stands).
From the Test Kitchen
Temperature is very important to the success of this frosting. Be sure to calibrate your candy thermometer before beginning. To do this, bring a saucepan of water to boiling. Check the temperature your thermometer registers in the boiling water. Add or subtract how many degrees off it is from 212 degrees F when measuring temperature of frosting.