I made this frosting for Wyatt's 1st Birthday Cake - it was a Pineapple Pound cake with Coconut Creme Filling. Buttercreams can be a bit tricky - but just be patient - and don't add the cold butter until the meringue is completely cooled. I fill two ziploc bags with ice cubes and hold them to the sides of the mixing bowl to help the cooling process along. Even still - it takes a good 10 minutes of whipping before it is time to add the butter. You can use a hand mixer (if you want a great arm workout!) but it is easiest if you use an electric one.
You will need a candy thermometer. They are sold in the baking aisle of most grocery stores. The brand of coconut cream I like to use is called Pepe Lopez. It is sold in a can and is found in the drink aisle at most grocery stores (because it is most often used to make Pina Coladas!) If you can't find Cream of Coconut, you can use Coconut extract instead.
4 large egg whites at room temperature
1/2 teaspoon salt
1 1/4 cups sugar
1/2 cup water
1/2 teaspoon fresh lemon juice
3 sticks (1 1/2 cups) unsalted butter, cut into tablespoon pieces
1 1/2 teaspoons cream of coconut
Combine egg whites and salt in bowl of a standing electric mixer.
Stir together sugar and water in a small heavy saucepan and bring to a boil over moderately high heat, stirring until sugar is dissolved.
When syrup reaches a boil, start beating whites with electric mixer at medium-high speed.
Once whites are frothy, add lemon juice and beat at medium speed until they just hold soft peaks. (Do not beat again until sugar syrup is ready.)
Meanwhile, put candy thermometer into sugar syrup and continue boiling, without stirring, until it reaches soft-ball stage (238–242°F)
Immediately remove from heat and slowly pour hot syrup in a thin stream down side of bowl into egg whites, beating constantly at high speed.
Beat meringue, scraping down bowl with a rubber spatula, until meringue is cool to the touch, about 10-15 minutes. (It's important that meringue is fully cooled before proceeding.)
With mixer at medium speed, gradually add butter 1 piece at a time, beating well after each addition until incorporated. (If meringue is too warm and buttercream looks soupy after some butter is added, chill bottom of bowl in a larger bowl filled with ice and cold water for a few seconds before continuing to beat in remaining butter.)
Continue beating until buttercream is smooth. (Mixture may look curdled before all butter is added, but will come back together before beating is finished.)
Add coconut creme and beat 1 minute more
**If you want to tint this frosting for decorating a cake, it is best to use food color gels rather than liquids, so as to not thin out the consistency.**