Seven-minute frosting is the stuff of legend, at least for those of us of a certain generation—the pillowy white cloud of frosting our grandmothers spread over and between layers of cake. Every bite was a shock of marshmallow sweetness, little more than sugar and air, with nothing but a whisper of vanilla for flavor.
The simplicity of its ingredients, along with the speed of its preparation, made seven-minute frosting a common companion to cakes with a more complicated profile, such as gingerbread, coconut layer cake or devil's food.
Like any of those old recipes that evolved in the American kitchen, definitions remain conceptual rather than rule-bound, based on intuition rather than training. But the truth of the matter is that seven-minute frosting is a Swiss meringue in disguise; that is, a combination of egg whites and sugar cooked over a water bath and whipped into a glossy meringue.
The ratio of ingredients in any Swiss meringue will vary from baker to baker, and purpose to purpose, as the amount of sugar affects not only sweetness but stability and volume. The amount of sugar and egg whites I'll use for Swiss buttercream differs from the ratios I lean on for pie, and that same variation is found within the microcosm of seven minute frosting as well.
Classic recipes call for sugar and egg whites in proportions ranging from 2:1 all the way to 5:1 by weight, and it's these high sugar recipes that are the norm. Yet the meringue itself becomes increasingly fluffy and light as the amount of sugar falls, but this lightness comes at the cost of stability, as it's sugar that keeps the moisture of the egg whites in check, and the meringue aloft.
In my extensive testing on the behaviors of Swiss meringue I found that relatively low proportions of sugar to egg whites (2:1 or less) can be quite stable when cooked to temperatures well above the 140°F generally called for in most recipes.
The exact ratios I use vary depending on the application, and that variation in turn affects the ideal cooking temperature of the meringue, as sugar raises the coagulation point of egg whites. For a seven-minute frosting, I've found that 2 parts sugar to 1 part egg white, cooked to 175°F, hits the sweet spot (or the not too sweet spot) of volume and stability, giving me a thick and creamy meringue that won't crust over in time.
You can also change the flavor of seven-minute frosting by using different types of sugar—with brown sugar it becomes sea foam frosting (without question, the loveliest name of any dessert). Beyond that, any type of raw sugar can be used as well (for more info, see our guide to raw and semi-refined sugar). My personal favorite is lightly toasted sugar, which serves primarily to round out the sweetness of the frosting, but darker styles work equally well if you'd like some stronger caramel notes.
Regardless of the sugar type, the method is just like any other Swiss meringue. If you've made one before, you know the drill, but for those new to the style (or who have struggled with it in the past), the basics go like this: Combine sugar and egg whites in a bowl, place them over a pot of steamy water, and stir constantly with a flexible spatula until the mixture is hot.
I like to use the bowl of my stand mixer, but it's worth noting that I use (and recommend) a bowl-lift mixer. Tilt head styles have a heavy foot on the bottom of the bowl, a poor design choice that causes the bowls to retain heat for unreasonable periods of time, wreaking havoc on what's inside. For this style of mixer, a separate bowl will need to be used for the water bath.
In any event, the cooking stage shouldn't take longer than ten to twelve minutes; this time range doesn't quite have the same snappy phrasing and timing suggested by the recipe's name. Just as Prometheus brought fire to change the world, the knobs on our stove give us dominion over heat, putting us in control of the entire process. When a thing cooks too slowly, we can increase the heat, and thereby speed up the process.
There is absolutely no reason to stand around for 45 minutes waiting for the temperature to creep up one fraction of a degree at a time. In fact, extended cooking times will ruin the meringue, as the warmth will be enough to drive off moisture via evaporation, resulting in a dry and gritty meringue.
When cooked at proper heat, Swiss meringue (of any stripe) is quick and easy, with the egg whites first warmed up in a few minutes on the stove, then whipped up with a stand mixer to produce a thick and glossy frosting.
Seven-minute frosting can also be seasoned to taste with salt, taming its sweetness, so don't feel married to the listed amount. In this (or any) recipe, the amount of salt given is a starting point at best, as the exact salinity per teaspoon will vary from brand to brand, while what's needed will vary from person to person. Remember there's no need to suffer through a frosting that tastes tooth-achingly sweet when an extra pinch of salt or two will round it right out.
While seven-minute frosting is most commonly flavored with vanilla extract, it's amenable to being seasoned with all sorts of extracts, essential oils, flower waters, and powders. When working with other flavors, bear in mind that essential oils and oil-based extracts should be folded into the frosting by hand at the very end, as their fat content may lead to deflation in the meringue.
After seasoning and flavoring, use the frosting right away and serve the cake as soon as you can. Seven-minute frosting's advantage is that it's fast, not long-lasting. It doesn't hold for much longer than 24 hours at cool room temperature. And no, refrigeration won't help.
The problem isn't perishability, but moisture and volume loss, as the cake is eager to wick moisture from the frosting, causing it to slowly dry and deflate. Meanwhile, the sugar in the frosting is eager to draw what it can from the cake. For example, the frosting will slowly turn red along the edges of a chocolate cake, as it pulls out the anthocyanins in the cocoa.
Due to these exchanges, seven-minute frosting isn't a good candidate for a make-ahead option—that's what buttercream is for!
But if you need a quick and simple frosting fast, it'll get the job done with minimal ingredients and fuss. Just remember that you're in charge of the fire, salt, and flavor, so don't hesitate to bend this frosting to your will. With the right adjustments, it will be creamy, light, and none too sweet.