Italian Meringue Buttercream
1 1/4 cups sugar
5 large egg whites
Pinch of cream of tartar
1 pound (4 sticks) unsalted butter, chilled
1 teaspoon pure vanilla extract
1. In a small saucepan over medium heat, bring sugar and 2/3 cup water to a boil.
Continue boiling until syrup reaches 238 degrees on a candy thermometer (soft-ball stage).
2. Meanwhile, place egg whites in the bowl of a standing mixer fitted with the whisk attachment, and beat on low speed until foamy.
Add cream of tartar, and beat on medium-high speed until stiff but not dry; do not overbeat.
3. With mixer running, add syrup to whites in a stream, beating on high speed until no longer steaming, about 3 minutes.
Add butter bit by bit, beating until spreadable, 3 to 5 minutes; beat in vanilla.
If icing curdles, keep beating until smooth.Italian Meringue Buttercream recipe and Video.