Now, it's not as easy as a plain old buttercream frosting made by beating butter, powdered sugar, and vanilla together. It requires cooking a sugar syrup and then slowly adding it to beaten egg whites, making a lovely meringue, and then adding softened butter.
You start by separating 5 eggs - you will be using only the whites, which you should place in a large bowl. Now, taking 1 1/4 cup extra fine sugar ( you can just run regular sugar through the coffee grinder for a few seconds ) and 1/4 cup water in a small saucepan, cook these together until the syrup reaches a temperature of 238* on a candy thermometer or the soft-ball stage when a tiny bit is dropped into a glass of cool water. Remove from heat.
While the sugar syrup is slowly cooking, beat the 5 egg whites until stiff. Once the egg whites are stiff and the sugar syrup is at the soft-ball stage, slowly pour the sugar syrup into the egg whites, beating all the while, until you have a nice meringue. Now, gently beat in 3/4 cup of softened butter. NOT TOO SOFT or your frosting will be wimpy. NOT TOO COLD or your frosting will be lumpy. Soft enough that you can begin to squish the butter with your fingers.
You can now place your buttercream in the fridge for a while, if you like. I think this makes it a bit easier to pipe.
The icing I have pictured here was a little too soft, but still tasted wonderful. Don't worry if you don't get it right the first time. It takes a bit of practice, but it's well worth the effort. I finally had to quit practicing, though, 'cause it was really ruining my diet!
5 eggs, separated
1 1/4 cup superfine sugar
1/4 cup water
3/4 cup butter
1 tsp vanilla (optional)