Classic Swiss Meringue Buttercream

Prep the equipment

1. Make sure all the whisks, spatulas, bowls and temperature probe are clean and dry with no fat residue. You can rub the bowls and other equipment with a lemon wedge or a paper towel with a little vinegar just to be sure. Then wipe clean with a clean paper towel. This will help get rid of any fat residue.

Separate the egg whites

1. Separate the egg whites from the yolk while the eggs are still cold, which makes it easier to do.
2. Make sure the egg whites are separated into a clean, dry bowl. Separate the yolks into a different bowl. Repeat with all the eggs until you have 250 g of egg whites.

Cook the egg whites and sugar

1. Transfer the egg whites into a large metal bowl (or metal mixer bowl). Again, make sure the bowl is clean and dry with no fat residue.
2. Add the sugar to the egg whites and whisk gently to just mix through.
3. Position the bowl over a pot of simmering water, and whisk continuously (does not need to be vigorous), while heating the mix. It’s important to keep the egg white mix moving in the bowl to prevent the eggs from scrambling.
4. Whisk the egg whites and sugar until the sugar has completely dissolved. You can check this by rubbing a little of the mix between your fingers. If there’s no grainy texture, then the sugar is completely dissolved.
5. Cook the egg white-sugar mixture for a further 3 - 5 minutes, or until the temperature of the egg syrup registers between 165 - 175°F (74°C - 79°C).
6. Remove the bowl from the heat, and manually whisk for a few minutes to cool down the egg whites slightly.

Make the meringue

1. Place the mixer bowl with the egg white syrup in your stand mixer, and attach the balloon whisk. Whisk on high speed (speed 8 - 10) until it has at least doubled in volume. The egg whites should form into a thick, glossy marshmallow-like meringue with stiff peaks. Add the salt and keep whisking. The heat should dissolve the salt.
2. Keep whisking the meringue until it has cooled down to about 80°F (26.6°C). The bowl should feel cool to the touch at this point.

Add the butter

1. Cube the unsalted butter, and have it ready to go while the egg whites are whisking.
2. With the whisk attachment still in place, add the butter - 1 to 2 tbsp at a time, and whisk the butter in at medium speed (5 - 7 speed). Don’t add all of the butter at once, only add it as the previous addition is getting mixed in well.
3. Once you start adding the butter, the meringue will deflate considerably and be very “soupy”. Also, the buttercream may appear curdled or look like cottage cheese. This is OK. Continue to add and whisk in the butter, and the mix will thicken up and become fluffy as the buttercream cools down and the butter mixes in thoroughly.
4. Add the vanilla and any other flavoring extracts halfway through the addition of butter.
5. Once all the butter is added and mixed in thoroughly, the buttercream should be creamy and fluffy. It may look a little lumpy (but without any butter lumps).
6. Switch from the balloon whisk to the paddle attachment, and mix the buttercream for a few minutes to get a smooth, creamy buttercream.
7. The buttercream is now ready to be used.