Fluffy White Cake with Swiss Meringue Buttercream

Fluffy White Cake with Swiss Meringue Buttercream.

Hey all!  Welcome to Day 3 of my Back to Basics Series!  I hope you are all following along, learning a thing or two about cake baking and frosting making, and enjoying some awesome go-to recipes.  In case you missed anything, we talked all about CHOCOLATE and all about BUTTER earlier this week.  Also, don’t forget to enter the giveaway!  You can find the entry form at the bottom of this post for your chance to win a signed copy of Layered: Baking, Building, and Styling Spectacular Cakes.  But until then, let’s talk all about EGGS.

At the end of Wednesday’s recipe for Classic Vanilla Cupcakes, I added a note about converting the recipe to make layers cakes, but how I typically use more egg yolks than whole eggs in my layer cake recipes to keep them extra moist and tender.  Unknowingly I’m sure, a kind reader asked why is it that sometimes I use whole eggs and other times I decided to use just the yolks.  Great question, right?  Well today, we are going to talk about just this- plus a few more tidbits about what happens to eggs in the oven and how to whip egg whites into heavenly clouds.

Fluffy White Cake with Swiss Meringue Buttercream.

All About EGGS
The checker at Costco must think I am totally crazy every time I unload at least 4 dozen organic eggs out of my cart and onto the conveyor belt.  At the rate I bake cakes and rely on poached eggs to make pantry staples and whatever vegetables we have left in the fridge into a full meal, we go through a ton of eggs.  But what is really in an egg and why do we depend on them so much for making delicious pastries and lazy weekend night meals?

Crack one open and it’s pretty obvious what you will find - a rich, golden yolk and runny, alien-like whites.  Most of time you see me cracking eggs, the shells are brown.  I use organic chicken eggs - the shells up here in Canada just happen to be that color.  I heard once that the shell color had something to do with the diet of the hen, but I don’t really know for sure.  Unless otherwise stated, most recipes call for large eggs.  If the egg (white or yolk) is measured by weight, then that is a pretty good indication that precise measurements are important.  For example, recipes for French macarons usually list egg whites in ounces or grams, because the the measurements need to be precise to create those crispy, finicky shells, and while eggs are separated into medium, large, and extra large, there is definitely some inconsistency in size.

WHITES VS. YOLKS
Besides the obvious differences in appearance and texture, egg whites and yolks play drastically different roles in the pastry kitchen.  As a whole, eggs create structure and stability within a batter, thicken and emulsify custards, and add moisture in the form of fat in cakes, cookies, and other baked goods.  There is some overlap, but let’s take a look at the parts separately first to better understand their functions.

The most important role of the egg yolk is to provide fat.  Fat adds richness, flavor, color, and gives cakes a velvety, tender texture.  This is why you will see that my go-to butter cake recipe only contains egg yolks.  The results are a golden, moist, and velvety crumb.  Another big attribute is their emulsifying abilities.  As an emulsifier, the yolks have a unique ability to help bind other fats and liquids together resulting in a more homogenous batter.  So in theory, if you want to add a bit of richness, try substituting whole eggs for yolks in equal amounts.  

For as awesome as egg yolks are at adding lusciousness, egg whites are at building structure.  Hard boil an egg, and you can see what heat does to an egg white - it firms up!  Whip ‘em, and they become mighty and strong but incredibly light.  Whipped egg whites act as natural leavening agents in certain types of cakes and soufflés.  In batters used for things like particular sponge and genoise cakes, the heat of the oven causes the air trapped in the foam to expand and the batter to rise without needing a chemical reaction like those created with baking soda or powder.  Some recipes still rely solely on whipped egg whites as leaveners while other use a mix of whipped eggs and baking soda/powder for reassurance.

Cakes made with whipped egg whites and without yolks (think Angel Food cake) tend to be light and airy in texture and pale in color.  Pretty great, right? For whom doesn’t love cloud-like layers of cake topped with things like whipped cream and fresh berries? However, like in most cases, there can be too much of a good thing.  Where egg yolks at moistness from fat, egg whites tend to do the opposite.  Too many egg whites in a batter can wind up making the cake dry.  Likewise, it is possible to over-whip your whites (more on how to whip in just a second), causing them to be clumpy, grainy, and difficult to work with.

Many recipes call for both or rather, just whole eggs.  When the eggs are separated and whites are whipped, you are essentially getting the best of both worlds - rich, fatty yolks and lightness from the whites.  Lots of recipes will just call for the whole egg to be added in - simple and straightforward.  

Fluffy White Cake with Swiss Meringue Buttercream.

WHIPPED EGG WHITES
All this talk about the role of whipped whites, but how do you actually achieve them?  Pretty simple, really, as long as you have an electric mixer.  Sure you can do it by hand, but why?  Haha.  There are a few things to note about whipping egg whites.  One, whipped whites wait for nobody.  They begin to break down and the air bubbles start to deflate once the whipping stops.  You will have some time, of course, to fold them into your batter, but it is best to have most everything prepared first.  However, you can help stabilize and strengthen the whites by adding cream of tartar, lemon juice, or reserving a tablespoon or two of granulated sugar. Adding these supporting ingredients also help maximize the volume of the whipped whites.  

While these few supporting ingredients are great at strengthening the whites and allowing them to stretch and expand, all other add-ins will hinder the foaming process.  Fat here is our worst enemy.  And as you may recall, egg yolks are essentially fat.  Be sure to separate your eggs with care and definitely pick out any bits of yolk that may have dripped in.  Likewise, make sure that your equipment is clean, dry, and free from grease.

To whip, start slow and increase the speed as the whites build.  You will want to use a whisk attachment.  Once the egg white begin to foam, gradually increase the mixer speed to medium-high/high.  And remember, it is possible to over-whip, so don’t get too carried away and be sure to stop at stiff peaks.

Fluffy White Cake with Swiss Meringue Buttercream.

MERINGUE
Simply add sugar to whipped whites (in one form or another) and you’ve made a meringue.  There are several different types of meringues used in the pastry world, so let’s take a look at a few:

French Meringue: This classic meringue is pretty straightforward - just egg whites beaten with sugar and cream of tartar.  When baked low and slow, it becomes crispy, airy, and sometimes chewy in the center.  Everything whips together with just an electric whisk to stiff, glossy peaks, then the meringue is either piped or spooned onto a baking sheet.  It is the type of meringue that bakes into cute meringue kisses, heavenly pavlova shells, and decorative shapes (think meringue mushrooms on a Yule log).  Unlike Swiss and Italian meringue, it bakes up hard, dry, and crisp.

Swiss Meringue:  Instead of being baked, the egg whites are heated with sugar and gently cooked over a double-boiler.  Once the egg white/sugar mixture is heated and the sugar begins to dissolve, it is whipped up on high speed until stiff and glossy.  The whipping cools the mixture in about 5 to 8 minutes (hello 7-minute icing!).  On its own, Swiss meringue is similar to marshmallow fluff and can be used to top things like Baked Alaska.  Add unsalted butter, and you’ve got my beloved Swiss meringue buttercream!

Italian Meringue:  Similar to Swiss meringue, Italian meringue uses heat prior to whipping and stays soft and fluffy.  However, instead of being cooked over water, the sugar is cooked with water.  Here, the egg whites are whipped separately while a sugar/water syrup boils on the stove top.  Once hot, the sugar syrup is streamed into the egg whites (while whisking on high), then mixed until stiff, glossy, and cool.  Like Swiss meringue, it is the base for buttercream and can be used to top pies and other pastries.

Last lesson, we took a closer look at American buttercream, but today let's visit my favorite, Swiss meringue buttercream!  And hey look!  I even made you a video about it:

SWISS MERINGUE BUTTERCREAM
If you read this blog often, then you've probably heard me sign he praises of SMBC a thousand times by now.  In my opinion, is isn't too difficult to make and is far superior to American buttercream.  I love the way it glides over layer cakes creating crisp edges and smooth swoops alike.  This is probably way it is so popular with pastry chefs and cake makers.  It is easy to flavor (passion fruit and Earl Grey are my favorites) and isn't too sweet.  As mentioned earlier, it is made by heating egg whites and sugar together over a double-boiler, then whipping it up to glossy meringue.  While the mixer is running on low, add in softened butter and combine into luscious perfection.

PROS
Not too sweet and easy to flavor; silky smooth and easy to frost/pipe with; moderate skill level

CONS
A bit fussier than American buttercream; requires using the stove; not as stable as Italian meringue buttercream; some might find it tastes too buttery

Fluffy White Cake with Swiss Meringue Buttercream.

Here I go talking about whipping egg whites into billowy clouds of goodness before carefully folding them into a batter, but this recipes simply call for them being add straight into the batter using the two-step or “reverse” method (as opposed to creaming - see previous post).

Fluffy White Cake
adapted from Layered

5 large eggs whites
1 teaspoon vanilla extract
3/4 cup whole milk
2 1/2 cups cake flour
1 1/2 cups sugar
1 tablespoon baking powder
1/2 teaspoon salt
3/4 cup unsalted butter, softened

Pre-heat oven to 350 degrees.  Grease and flour three 7-inch cake pans and set aside

In a small mixing bowl or liquid measuring cup, stir together the egg whites, vanilla, and 1/4 cup milk and set aside.

Sift together the flour, sugar, baking powder, and salt into the bowl of an electric mixer.  With the paddles attachment, mix on low until combined.  Add the butter and remaining 1/2 cup milk and mix on low until the dry ingredients are moistened.  Turn the mixer to medium-high and mix until combined.  Stop the mixer and scrape down the bowl.

With the mix running on medium-low, gradually stream in the egg white mixture.  Work in about 3 batches, making sure everything is incorporated before adding in more liquids, scraping the bowl in between additions.  Each addition of egg whites should take about 10 to 15 seconds to stream in in order to emulsify properly, but do not over-mix or the cake may become dry.

Evenly distribute the batter between the prepared pans.  Bake for 22 to 25 minutes, or until a toothpick inserted into the center of the cake comes out clean.  Cool on a wire rack for 10 to 15 minutes before removing the cakes from their pans.

Swiss Meringue Buttercream
makes about 3 ½ cups 

½ cup (120 ml) egg whites (from about 3 to 4 large eggs)
1 cup (200 g) granulated sugar
1 ½ cups (3 sticks – 340 g) unsalted butter, at room temperature, cubed
1 ½ teaspoons pure vanilla extract
½ vanilla bean, seeds scraped out (optional)

1.  Whisk together the sugar and egg whites:  In the bowl of an electric stand mixer, add the egg whites and granulated sugar.  Whisk them together briefly by hand, just until they are combined so that the egg whites don’t begin cooking by themselves.

2.  Create a double-boiler:  Fill a sauce pan with a few inches of water and bring to a simmer.  Place the mixer bowl with the egg white mixture on top to create a double-boiler. The water should be kept at a simmer but should not touch the bottom of the bowl.  The double-boiler acts as indirect heat for the egg white mixture. 

3.  Heat the egg white mixture:  Occasionally stirring, heat the egg white mixture until it reaches 155 to 160 degrees F on a candy thermometer.  The mixture should be very hot to the touch and the sugar should have dissolved. 

4.  Make the meringue:  Once the egg white mixture is hot, carefully return the bowl to the stand mixer.  Fitted with the whisk attachment, beat the mixture on high speed for about 8 minutes.  When done, the meringue should hold shiny, medium-stiff peaks and be cooled to room temperature.  Stop the mixer and swap out the whisk for the paddle attachment.

5.  Add the butter:  With the mixer on low, begin adding in the butter a couple tablespoons at a time.  Use the paddle attachment to mix it in.  The butter must be room temperature in order to incorporate properly with the meringue.

6.  Add the vanilla:  Once the butter has been mixed in, add the vanilla bean seeds (if using) and the vanilla extract.

7.  Mix until smooth:  Turn the mixer up to medium speed and mix until silky smooth.  This may take a few minutes, but centime to mix until light, creamy, and free from most air bubbles.

For a more in-depth look at Swiss Meringue Buttercream, click here.
 

Lastly, don't forget to enter the giveaway!