This is the one I reach for most in a professional kitchen. It's built the same way as Swiss meringue buttercream, but the hot-syrup method makes it noticeably more stable — which matters a lot on a warm event day.
by Alejandro, PastryPath · Updated October 2026
Italian meringue buttercream and Swiss meringue buttercream get compared constantly, and honestly, they taste and behave very similarly once they're finished. The difference is in the method: instead of gently heating egg whites and sugar together, you cook the sugar into a syrup separately and stream it into whipping egg whites. That extra step buys you two things — a more stable finished buttercream that holds up better in a warm room, and a meringue with noticeably fewer air bubbles.
The syrup needs to hit exactly 240°F / 115°C before it goes in — pull it too early and the buttercream will be loose; too late and it can seize into hard sugar threads. Once it's at temperature, pour it in a thin, steady stream aimed at the space between the whisk and the side of the bowl, never directly onto the moving whisk (it'll fling hot sugar) and never straight onto the bowl's side (it can harden there instead of incorporating).
Usually the meringue was still warm when the butter went in, or the butter was too soft. Make sure the meringue is completely cool at the end of whipping (step 5). If it has already turned soupy, chill the bowl for 10–15 minutes, then whip it again until it comes back together.
That's normal while the butter is going in (step 7). Keep mixing and it will smooth out into a silky buttercream. If it stays split, the mixture is usually too cold: warm the outside of the bowl briefly and keep whipping.
240°F / 115°C. Pulled too early, the buttercream will be loose; too late, and the syrup can seize into hard sugar threads. Stream it in slowly between the whisk and the side of the bowl.
Both are silky meringue buttercreams. Swiss gently heats egg whites and sugar together; Italian cooks the sugar into a hot syrup and streams it into whipping egg whites, which makes it more stable in warm rooms. See the Swiss meringue buttercream recipe, or compare all six in our types of buttercream guide.
Refrigerate it for up to a week. Bring it to room temperature and re-whip before using.
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