This is a recipe I got from a good friend, Melissa Kearl, who bakes wedding cakes and other desserts semi-professionally. Buttercream frosting is useful in numerous applications such as icing cakes, pastries, to serve as a rich filling and as a decoration.
|½ tsp||cream of tartar|
|2½ cups||butter, soft and unsalted|
|1 tbsp||vanilla extract|
1. Stir the sugar, water and salt in a heavy 3-quart saucepan over medium heat until sugar dissolves.
2. Attach clip-on candy thermometer to side of pan. Increase heat to high. Boil without stirring until 235-8°, brushing down any sugar crystals that form on the sides of the pan with a pastry brush dipped in water. This step takes about 25 minutes.
3. Meanwhile, beat the egg whites with the cream of tartar in a clean metal bowl until medium stiff. This should be done about 20 minutes into the previous step. That it get done too soon isn't too crucial, but you do not want to let the candy from step 2 sit around waiting for the whites to be whipped.
4. While mixer is still running from step 3, gradually add in the hot syrup from step 2 keeping the stream steady. Continue beating until meringue is barely lukewarm, about 8 minutes.
5. Beat in the butter, 2 tbsp at a time. Continue beating until light and fluffy, about 10 minutes.
6. If the frosting looks curdled, place the bowl briefly over very low heat and whisk it until the butter softens just a bit.
7. Beat the buttercream with the mixer until smooth at this point repeating step 6 as necessary.
8. Mix in the vanilla and transfer to another bowl where it must stand at room temperature until used.