How to Make Chef Thomas Keller's Swiss Meringue Recipe

A meringue is a foam of air bubbles enclosed in egg white and stabilized by sugar, first developed in the 17th century by cooks who used bundles of straw as whisks. Nowadays, we tend to whip our whites in a stand mixer, but there’s still a bit of technique involved in making meringue.

One of three classic meringue-making methods, marshmallow-y Swiss meringue, aka meringue cuite, is made by beating egg whites and sugar together in a double boiler (a pan or bowl set above boiling water) until sugar is fully dissolved and the mixture is hot to the touch. It’s then removed from heat and further beaten until doubled in volume.

Swiss meringue can be baked into cookies or shells for desserts like pavlova and eton mess, but because it’s heated, it doesn’t need to be baked. Swiss meringue is stable enough to fold into buttercream frosting or top lemon meringue pie and baked Alaska.

Although they’re made with the same basic ingredients—egg whites and sugar beaten to a stiff peaks—Swiss meringue differs from the Italian and French styles in a few key ways: It’s smoother and denser than French meringue, but less stable than Italian.

Swiss meringue tends to achieve less volume than the other varieties, because the sugar is added early on in the whipping process, interfering with the egg proteins’ ability to unfold and bond with each other to form the walls that support the little bubbles of air. Since you don’t need to make a hot sugar syrup, Swiss meringue is less maintenance than Italian, but also less stable. Regardless, it's more stable than French meringue, which must be baked to hold its shape.

There’s a lot that can go wrong when trying to force liquid egg whites into a solid-like foam. Set yourself up for success:

• Use a large mixing bowl, at least eight times bigger than the starting amount of egg white.
• Use a copper or silver-plated mixing bowl, or add a pinch of powdered copper supplements.
• Make sure your egg whites are free of any traces of yolk and that your mixing bowl and whisk are clean and dry.
• Using a large pot—bigger than your mixing bowl—will help keep the water at a low simmer. Make a ring of foil to keep the pot above the water line.
• Don’t skimp on the sugar—it’s not there just for flavor. Sugar bonds to water and slows its evaporation, so if there’s not enough sugar in your mixture during baking, the water in the egg whites will evaporate before the egg proteins have time to form a stable structure around the air bubbles. You can also use cornstarch to mimic the effects of sugar. (Powdered sugar already contains about 10 percent cornstarch.)
• Although not strictly necessary, there are a couple of stabilizing agents you can use to prevent “weeping,” or separation of the water, which happens when the proteins in the egg whites bond too tightly to each other. Once the egg whites just start to develop some structure, add an acid in the form of ⅛ teaspoon cream of tartar or ½ teaspoon lemon juice per egg white.
• The more powerful your whisking, the more quickly the egg whites will aerate. Do yourself a favor and use a large, balloon-style whisk or, even better, an electric mixer.
• A flexible rubber spatula will help prevent any sugar from sticking to the sides and bottom of your mixing bowl during the first whisking.
• To make the quenelles in this recipe, set an ovular, deep-bowled spoon in hot water. Glide the spoon, round side angled down, over the meringue to form a neat egg shape. You can also pipe or spoon the meringue into any other shape.
• If baking meringues in an electric oven, leave the door slightly ajar.
• Always store baked meringues in an airtight container: Since sugar attracts moisture from the air, meringues left exposed to humid air will form beads of sweat.