Swiss Meringue Buttercream
* 2 cups granulated sugar
* 10 egg whites
* 2 lbs. unsalted butter
* 1 tbsp. vanilla
* 1 pinch salt
1) Find a pot that your mixer bowl can rest on top of without touching the bottom. Fill this with enough water that when the bowl in sitting on top of it, it’s not touching the bottom of the bowl. Bring this to a simmer on the stove. Meanwhile, put the sugar, egg whites, and salt into the mixer bowl. Don’t separate whole eggs for this recipe to get the egg whites.
2) Put the mixer bowl of egg whites and sugar over the simmering water (now a bain marie) and whisk lightly while heating until they reach 150◦F. Use your candy thermometer to monitor the temperature. If you don’t have a candy thermometer, you can test with your finger: the egg whites should feel hotter than warm but not painfully hot and if you rub it between your fingers, you wouldn’t be able to feel any sugar crystals. Transfer the bowl to the mixer and with the whip attachment, start whipping! You’ll likely find that you need to start slow (around 3 or 4 on my stand mixer) until they get frothy and then bring the speed up (to around 8). Continue whipping 10 – 15 minutes until you have a meringue with stiff peaks that is cooled.
3) Now, switch to the beater attachment on your mixer and start adding the butter, a bit at a time, until it’s entirely incorporated. If your buttercream starts to look soupy part way through, that’s normal. Just keep beating. If the buttercream starts to look curdled part way through, that’s also ok. Just keep beating. Does something feel strange about it and you’re certain you’ve made a mistake and you’ve been beating for a couple of minutes and nothings changing? Also normal. Just keep beating.
4) Add the vanilla, or flavouring of your choice (sky’s the limit but we tend to make a lot of lemon around here) and continue to beat until well mixed. The buttercream is now ready for your cake! It can be made up to a week in advance and stored in an airtight container in the fridge. It also stores well in the freezer for about 3 months. Leftovers top cupcakes quite nicely, I find as well. If your buttercream is cold, be certain to give it time to properly return to room temperature before you use it. You can beat it again just prior to frosting if it’s been chilled.
5) Temperature is something you might want to think about when making buttercream. I live in a house that’s cool in the winter (< 18C) and downright hot (> 30C) in the summer. I sometimes have to fight these temperature swings when making buttercream. If you also live in this kind of environment, keep reading for tips on how to get your ingredients and your meringue at a more typical room temperature.
6) For your butter, once it’s cut into pieces: if you poke the pieces and they completely mush, the butter is too warm. If you poke the pieces and your finger makes no indent whatsoever, the butter is too cold. If the butter is too warm, you can cool it for a few minutes in the fridge while you prepare the meringue. If it’s too cold, you can wait a little longer and check again before starting the meringue, or if you’re brave, pop it in the microwave for short, < 20 second cycles, at 50% power until it’s softer.
7) For your meringue: Touch a bit of meringue onto your bottom lip. It should feel just slightly cool. If that’s the case, you’re ready to go. If the meringue is still a tad hot you can put it into the fridge for 5 minutes (no more!) or continue to whip for a minute or two while holding an ice pack along the sides of the bowl. It’s over 30 degrees Celsius right now in my city and I don’t have air conditioning. I had to use a bag of frozen peas to cool down this bowl of meringue – it’s that DAMN HOT (just as an aside). If your kitchen is actually ‘temperate’, beating the meringue for 10 to 15 minutes should produce a meringue with perfect peaks and at just the right temperature.
8) For your buttercream: If you added the butter and it was a bit too cold, it may take a lot of beating to get rid of the curdled look and move on to the smooth stage. A pair of warm hands, or a wash cloth that’s been soaked in hot water placed around the sides of the bowl will bring everything back up to the right temperature reasonably quickly.