The first time I made buttercream with boiled sugar, I made whole egg eggnog buttercream. I loved it the moment I tried it. It is simply delicious. It's rich and velvety smooth. It carries flavour really well! Truth be told, I use my Italian Meringue Buttercream most often. Because it has a white base, it colours better. But every once in awhile I bust out this whole egg buttercream recipe, and I remember why I fell in love with it.
In a small saucepan, combine the sugar and ½ cup water. Place over medium heat and bring to a boil. Clip a candy thermometer to the side of the pan.
While the sugar syrup is heating, put the eggs in the bowl of a stand mixer fitted with the whisk attachment.
When the syrup reaches 230 F on the candy thermometer, begin to whip the egg on medium-high speed. Whip until the eggs are frothy and light in colour. The idea is to get to this stage of the eggs being frothy and light by the time your syrup reaches 240°F and you can move to the next step.
When the syrup reaches 240F, immediately remove the pan from the heat and, with the mixer running, pour the syrup into the eggs in a very thin stream. Pour the syrup between the side of the bowl and the whisk attachment. Be very careful, this syrup is HOT! You do not want it to hit the whisk attachment and splash you.
Whip the eggs and sugar at high speed until thick and glossy and the bowl is no longer warm on the outside, about 8-12 minutes. The most important thing is that the mixture completely cools down, and when you touch the side of your bowl, you feel no heat. This may take longer for you, or it may happen faster.
With the mixer running, add the butter, a piece at a time, whipping until each piece is fully incorporated before adding the next. Scrape down the sides of the bowl with a spatula occasionally.
After all the butter has been added, add in the vanilla and continue to whip the buttercream until it’s thick and smooth, 3 to 5 minutes. Again, this may take longer! Often when adding the butter the mixture appears to deflate and even become soupy. Do not lose hope! Keep whipping!
Add your nutmeg and brandy, and whip until combined.
Use immediately or transfer to an airtight container and store in the refrigerator for up to 1 week or the freezer for up to 2 months. Before using refrigerated or frozen buttercream, let it warm up to room temperature and stir to smooth it out.