I have a KitchenAid stand mixer (classic version, cobalt blue). I love my KitchenAid. I would rescue my KitchenAid from a fire. But this frosting is the one mixing job my true love can’t do for me, so I have to keep a sleeker, more adventurous mixer on the side.
When I was little, birthday cakes got an extra-special slathering with a meringue-like substance known as seven-minute frosting or double-boiler frosting, and it was spectacular. The problem was, if you didn’t eat the whole cake on day one, the frosting separated into a hard sugar crust on top and a sloppy mess underneath that made the rest of the cake soggy and inedible.
The Marshmallow Frosting in The Cake Mix Doctor is basically the same fluffy cloud of sweetness, but adding the marshmallow fluff stabilizes this version of the frosting so the consistency remains the same even a week later. I took out a lot of sugar because the fluff brings plenty of its own, reduced the liquid because there’s less sugar to soak it up, and used the cooking technique from the old family recipe.
The Only Reason I Own a Hand Mixer Frosting
- 1/4 cup of granulated sugar
- 1 tablespoon of water
- 2 egg whites
- 7-ounce jar of marshmallow crème
- Optional: 1/2 to 1 teaspoon of flavored extract (see notes below)
In the pan of a double boiler, bring an inch of water to a simmer. In a large bowl, add sugar, water, and egg whites; place on top of double boiler. Beat with a hand mixer, starting at low speed and gradually increasing to high, for 7 minutes, at which point you should have stiff peaks (and a stiff shoulder). Remove the bowl from the heat. Slowly beat in marshmallow fluff. Spread on cooled cake.
Generously frosts a 13 x 9-inch sheet cake.
- The base flavor here is pure sugar, so this frosting takes other flavors really well. Try mint, orange, lemon, vanilla, almond, coconut, or any other extract you like—maybe even liquer, if you’re the boozy type. If you use more than a teaspoon, though, take away a corresponding amount of water to maintain the consistency.
- This frosting is pure white, so it also takes food coloring beautifully. Add a few drops to tint.
- You don’t need to go out and buy a double boiler. Put an inch of water in the bottom of a saucepan and set a heat-safe bowl on top. Don’t let the water touch the bottom of the bowl, and don’t let all the water evaporate. Keep it to a simmer; you don’t need a hard boil to get the steam to warm the bowl.
- If your mixer has a cord, be careful about keeping it away from the burner. I wrap the cord around my arm a couple of times or hook it through the utensil bucket (depending which side of the stove I’m on) to keep it safely elevated.
- Use a large mixing bowl, the biggest and deepest you can come up with. The sugar and egg whites part won’t give you any grief, but when you try beating in the marshmallow fluff, it’s going to fly everywhere. Even with my 4 L Pyrex bowl and the lowest mixing speed, I somehow end up with frosting on my back every time and days later find a glob on the handle of an overhead cabinet or fifteen feet down the hallway or something. Big bowl, and shield thyself by any means necessary.
- I’ve found recently that some brands of marshmallow fluff collapse the beaten egg whites a lot. If that happens, shake your arm out and just beat the hell out of it until the volume comes back, which it will do eventually.
- This frosting is very soft. It won’t hold a shape if you pipe it, and if you put it between cake layers, your layers will slide off (as the s’more cake that ended up on my floor could testify if only it hadn’t met a tragic end). It might hold up between cookies, but otherwise, keep it to exterior applications.
- The egg whites are theoretically cooked after seven minutes over the steam and I’ve never made anyone sick without testing the temperature, but mandatory food safety disclaimer: use clean, undamaged eggs and store this frosting in the refrigerator until just prior to serving.