May 23, 2012

The Quest for the Perfect White Frosting

I have never really liked buttercream. The plain stuff, made by whipping together powdered sugar and butter, has always been too sweet and too rich for my taste--at least in the volumes it usually shows up on top of store-bought cupcakes (think Magnolia Bakery). The fancy stuff--the meringue buttercreams--is better, but until recently it was a mystery to me. Despite several attempts, despite purchasing a candy thermometer, despite following directions from Irma Rombauer, from Deb Perelman, from Martha Stewart, as exactly as I could, it never really came together.

Until last week. I am making a wedding cake for a June 2 wedding for 150 people. I have made several wedding cakes before, including one last year for 180 people, but this one presents a new challenge. The bride wants white frosting. I have always used ganache. Ganache is my favorite kind of frosting. It is perfectly delicious and relatively easy to make a cake look good. But it is not white. For white frosting, there are six main options:

1) Fondant. Fondant makes for the smoothest (and most professional) wedding cake exterior, but I have never worked with it, and didn't think someone else's wedding, only a few weeks away was the best time to start).

2) White chocolate ganache (or buttercream). I just don't like white chocolate. It is not really chocolate at all. It is basically cocoa butter and sugar, which means it has all the sickly richness of milk chocolate with none of the subtle and intoxicating flavor of actual chocolate. Plus, it does not make for a pure white frosting. It is better if you want an ivory cake.

3) Meringue (or 7-minute icing). Just egg whites and sugar, meringue whips up like marshmallow. I love it, but I think it is too sweet for wedding cake.

4) Plain Buttercream. See above.

5) Cream Cheese Frosting. This is a step up from plain buttercream. The cream cheese cuts the sweetness a bit. I could eat it by the spoonful. But cream cheese can't sit out as long as butter can, and I was worried this might be dangerous choice for an outdoor wedding in a place without a refrigerator large enough to hold the entire cake.

6) Meringue buttercreams. There are several types. Swiss meringue buttercream is made by heating the dissolving sugar in egg whites over a water bath, then removing the mixture from the heat, beating it into a meringue, and then beating in the butter. Italian meringue buttercream is made by pouring a hot sugar syrup into egg whites as you beat them, and then adding butter. As I already said, I wrote this off for a long time, because I could never get it to produce a stable icing. Every swiss meringue buttercream I've tried (I've never made the italian kind) has had the same problem. The final product was runny. Here's why: when I transferred the egg whites and sugar to the stand mixer, I started adding the butter too soon. I would add it when it looked like the the meringue was complete (it formed stiff peaks and was glossy), but I wasn't giving the meringue enough time too cool. The butter was melting. It takes a long time, but you have to wait until the outside of the mixing bowl is completely cool to the touch. Thanks to Sweetapolita for solving this mystery for me.
Once I figured out how to make a stable buttercream, my next challenge was to make one I wanted to eat. This required cutting the butter substantially and adding something tart. I tried cream cheese first, but wasn't satisfied. Then I tried greek yogurt. This produced a buttercream that was rich, but light and not overly sweet. I am worried about how well it will hold up if it is a hot day, but I am going to keep the proportion of yogurt very low, and wait and see what the weather report looks like. A June early evening in Massachusetts could be 60 or 80. I may also give the Italian version a try, because I have read it is more stable than the Swiss version.
The final challenge was to make this with pasteurized eggs. There will be some small children at the wedding, and, while I am fairly confident that cooking eggs to a temperature high enough to melt sugar is also sufficient to prevent any food-borne diseases, I don't want to run that risk with other people's children. I bought some egg beaters. Unfortunately, it didn't occur to me to check the ingredients list, and it turned out that the egg beaters had beta carotene added for color, so they would look like real eggs, which meant they would not make white frosting. I tried anyway, thinking I would select my brand more carefully for the real deal, but the despite whipping and whipping and whipping, nothing happened. No volume. No stiff peaks. Nothing. I moved on to powdered egg whites. Despite some naysaying blogs warning me that these would never form a stable frosting (something to do with broken down protein strands), I found them to be a perfect substitute for real egg whites. See this comparison of the appearance of the egg beaters and the powdered whites.
So here it is, a buttercream I want to eat and am capable of making! Questions still to sort out: what variety of chocolate cake to make. What to fill the cake with. How to decorate the exterior. I brought the version pictured here to a one-year old's birthday. I will probably not go in the rainbow sugar direction for the wedding.

- Franklin
Yogurt Swiss Meringue Buttercream
Sweetness factor: 9; Indulgence Factor: 9; Difficulty Factor: 8; Chance I'll Make it Again: 10.
Total Time: 1 hour
Enough to frost a 9-inch layer cake, or two dozen cupcakes.

1 cup granulated sugar
4 egg whites or 8 teaspoons powdered egg whites dissolved in 1/2 cup water
20 tablespoons butter (room temperature, soft but not too smooshy)
2 tablespoons Greek Yogurt

Put the egg whites and sugar in the bowl of your electric mixer (or, if you are going to use a hand mixer, in a metal bowl). Set over a pot of simmering water. You only need an inch or two of water, and make sure the bowl isn't touching the water. Heat, whisking fairly frequently to prevent the egg from cooking solid, until the sugar dissolves completely. Go ahead and stick your hand in and rub two fingers together. If you don't feel any granules, it should be ready. If you have a candy thermometer, confirm that the mixture has reached at least 140 degrees (fahrenheit).

Remove from heat, set in the stand mixer with the whisk attachment. Whisk at medium speed until you have a stiff glossy meringue and the side of the bowl is completely cool. This may take a while, perhaps 15 minutes. Possibly longer if you have increased the volume of the recipe.

Replace the whisk attachment with the paddle attachment. Add the butter a few tablespoons at a time. Add the Greek yogurt. Beat until it comes together. See this website for some advice if it is not coming together. Decorate straight away or store in the refrigerator covered.

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