There are three types of meringue: their differences lie in when and how the sugar is added. There is French, Italian and Swiss.
Swiss meringue is made by stirring sugar and egg whites together over a pot of simmering water until they are very warm to the touch before whipping them. The early addition of the sugar prevents the egg whites from increasing as much in volume as they do in the other meringues, but adds to its fine texture. Swiss meringue is particularly good for baking crisp meringue cake layers and for topping pies.
That is why I am using this technique in this Swiss meringue buttercream recipe. It is so velvety smooth and sweet, ethereal and fluffy, but holds its shape and is ideal for piping and decorating your favorite dessert. It is also easier to achieve pristine white color with Swiss meringue rather than with Italian or French meringue techniques. The result is beautifully pure and snowy white buttercream.
Swiss meringue buttercream involves cooking eggs and sugar over a double boiler, whipping them into a meringue, then adding butter and flavorings.
Here is a couple of tips to make it easier for you.
I recommend using a stand mixer for this buttercream. You likely could do it with a hand mixer, but it would be a more painful process you’d be holding that hand mixer for a good 20+ mins.
To keep your meringue cookies pristine white make sure to beat your egg whites in a complete moisture and grease free mixer bowl. Oil is meringues enemy.
Also there should be no traces of egg yolks. In order to do this make sure to crack them on a flat surface, not the edge of your bowl, and separate them while cold, right out of the refrigerator.
The egg whites mixture needs to reach 160F to be considered fully cooked. If you are scared of raw eggs in your buttercream make sure to use a thermometer.
Whipping meringue takes about 8-9 minutes in a mixer. You will know it is ready when you see firm, glossy peaks.
After you cook your eggs and whip up the meringue you can start adding butter. Don’t get scared if it gets soupy first. It takes good 10 minutes of mixing for it to fully incorporate. And don’t forget to switch you mixer’s attachment from whisk to spatula.
In the end you can add the flavorings, extracts and colorings.