Swiss Meringue Buttercream: The Silkiest, Stable, Less Sweet Frosting

Instructions:

1. Prepare the Bain-Marie: Fill a medium saucepan with about 1 inch of water and bring it to a gentle simmer. Ensure the water does not touch the bottom of the heatproof mixing bowl placed on top.
2. Combine Ingredients: In the heatproof mixer bowl, combine the egg whites, granulated sugar, and salt.
3. Heat and Whisk: Place the bowl over the simmering water. Continuously whisk by hand until the sugar is fully dissolved (no grittiness) and the mixture reaches 160°F (71°C). This pasteurizes the egg whites. Remove the bowl from the heat and immediately transfer it to the stand mixer base.
4. Whip the Meringue: Using the whisk attachment, begin whipping the warm egg mixture on medium-low speed, gradually increasing to high. Continue whipping until the meringue forms very stiff, glossy peaks. Crucially, the exterior of the mixing bowl must feel completely cool to the touch (this may take 10–15 minutes).
5. Switch Attachments: Once cooled, stop the mixer and replace the whisk with the paddle attachment. Turn the mixer speed to low.
6. Add Butter Slowly: With the mixer running on low, add the very soft, diced butter, one cube at a time. Wait until each piece is mostly incorporated before adding the next.
7. Whip to Recovery: The mixture will deflate and look curdled or soupy (the “break” stage). Do not panic. Increase the mixer speed to medium-high. Continue whipping for 3–5 minutes until the mixture suddenly transforms into a thick, smooth, luscious Swiss Meringue Buttercream.
8. Final Flavours: Once smooth, stop the mixer and scrape down the bowl. Add the vanilla extract. Whip for 30 seconds more on medium speed until fully combined and light and airy.
9. Adjust Consistency (If Needed): If the buttercream is too soft, chill the whole bowl in the fridge for 10–15 minutes, then re-whip until the desired firm consistency is achieved.