In pastry school, we had a three-week class called “Contemporary and Modern Cakes”—and while the name sounds swooping and grand, it was essentially about how to prep, make, and assemble mousse cakes.
While there are endless variations on this concept mousse cakes are, at their most basic, essentially layer cakes where mousse is used instead of filling or frosting on the inside and on the outer edges of the cake. Because mousse is relatively fluid when first prepared, then sets up under refrigeration, these cakes can be made in molds—something that largely contributes to their “contemporary” or “modern” look. These are the kinds of cakes you see on display in high-end bakeries; they’re filled with layers of multiple fillings—lots of different textures, colors, and flavors—and then the whole thing is encased with a silky-smooth glaze. They’re usually finished with some seriously impressive garnishes.
These aren’t the easiest cakes to make, but it’s not because the components are too difficult; it’s just that there are several of them, some of which are temperature sensitive, so they have to be handled just right. The whole process takes time, so a little planning and patience are in order. But the bottom line is: You can absolutely make one of these cakes at home, and the results speak for themselves. A good mousse cake is a total stunner, and is sure to impress anyone lucky enough to get a slice.
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Mousse cakes have, at minimum, three components: cake, mousse, and glaze. You can always get fancy and have multiple layers of different cakes, or mousse—or even throw in some surprising elements, like a thin layer of caramel or some nut brittle to provide contrasting flavors and texture. But this recipe just sticks to the basics (and uses chocolate sprinkles to garnish… because sprinkles make everything better).
The upside is that the cake itself can be made ahead of time—so with a little planning, you’ve got less to do come assembly time. Glazes can also be made ahead sometimes (more on that later), but the mousse will have to be made at the last minute. You need to allow plenty of time for the assembled mousse cake to chill before it’s glazed, so just be sure to allow yourself enough time to pull this off. Plan it out, and it’s likely to go super-smoothly.
Mousse cakes are made using a mold. I use these handy metal cake rings I bought at a baking supply store—they're thin metal rounds that come in the same size as cake pans, and they’re super handy. But if you don’t have this kind of mold (I imagine most home bakers don’t!), there’s several other options. You can use the outer ring of a springform pan, which works great. If you happen to have silicone cake pans, those work too, and are pretty easy to unmold since you can just peel them away! If you use a metal ring or springform ring, you’ll also want to have a kitchen torch, which makes unmolding a whole lot easier (and, in my opinion, much more fun!).
Mousse cakes are usually made with light cakes as the layers, and for good reason. When you build the cake, you alternate layers of cake and mousse. If the cake is too heavy, it can actually sink a little into the mousse, messing up your layers by pushing the mousse upwards instead of creating a layered look. So no pound cake here: Stick to sponge cakes (you can soak the cake layers if you like) of any sort, or anything that boasts a light, airy texture.
Sour Cream Sponge Cake
- 3 eggs
- 1 1/2 cups sugar
- 1 teaspoon vanilla extract
- 3 cups all-purpose flour
- 3/4 teaspoon baking powder
- 1/4 teaspoon baking soda
- Pinch salt
- 1 1/3 cups sour cream
The layers of the cake should be smaller than the mold you’re using, because you need to leave room to fill in the mousse between the layers and on the sides of the cake during the assembly. I used a 9-inch mold, so I baked my cakes into 6-inch layers. You can also bake your cakes on a sheet tray, and cut out round layers from the flat cakes (this is something they do a lot in professional bakeries, and it makes nice, even, very flat layers—plus, thin baking sheet cakes take less time to bake)! If you’re using traditional cakes baked in a cake pan, let them cool, then cut off any domed top, and cut the cake into even layers. The layers can be any thickness as long as they can fit, with layers of mousse, in your cake mold. This cake had 3/4-inch layers, and the mold was 4 inches tall!
You can read all about mousse here, but the most important thing to remember is that regular mousse is usually poured or piped into a vessel like a glass, and then you eat the mousse with a spoon. If it’s a little soft, it’s no biggie; it’s still spoonable and full of whipped cream and sugar and all kinds of other yummy things. But you need to be able to slice your cake, so the mousse has to be relatively firm. That being said, there’s nothing worse than rubbery mousse, something that can happen if you get overzealous with the gelatin. It’s all about finding the balance: enough gelatin to make the cake stable, but still silky and soft when it comes time to eat it.
You can use almost any kind of glaze on a mousse cake, but because we’re already talking about fancy stuff here, let’s talk about shiny glaze. Shiny glaze is made with gelatin. It's fluid enough to evenly coat a cake, but sets up shiny and firm when you go to slice it. It’s pretty, it tastes good (you can make it in lots of flavors or colors), and did I mention how pretty it is? The only real downside to using shiny glaze is that it’s temperature sensitive. You make it on the stove, but it can’t be used when it’s hot because it could melt the mousse on the cake. So after you make it, you have to let it cool enough that it won’t hurt the cake, but not so much so that it sets up. 80 to 85° F is the sweet spot. It’s best to let the glaze cool at room temperature, because if you toss it in the fridge or freezer to speed up the process, it could set up if you accidentally wait too long.
If you are using another kind of glaze (maybe a thin ganache or something), you can make your glaze ahead of time. If it’s gelatin-based, it’s best to make it the same day you want to use it, as reheating and re-cooling can be tricky.
First things first: Most mousse cakes are built upside down. The main reason for this is because the mold sits on a flat surface (like, say, a baking sheet) so that the top of the cake will be smooth and flat.
Start by lining a baking sheet with parchment or wax paper, and place the mold on top of the paper. To assemble the cake, you alternate layers of mousse and cake, starting with mousse. Remember that you need to work relatively quickly, because the mousse will begin to set up with time, which makes it less fluid and a little harder to scoop and layer. I like to use a ladle to help me move the mousse from the mixing bowl to the mold; if it takes me three ladlefuls to get an even layer with the right amount of thickness, then I know I should use three ladlefuls on the next layer, too.
Make an even layer of mousse in the base of the mold (remember, this will eventually be the top!). The mousse layer should be about 1 1/2 to 2 inches tall, but no need to be precise. Take a cake layer and place it in the center of the mold. Press the cake down gently to make sure it’s flat and to help some of the mousse below it flood up the sides to encase the cake layer. Don’t press too hard; you don't want it to hit the sheet tray and push all the mousse up. If you want to soak the cake layer with a simple syrup (flavored with spices, vanilla, or booze), do it at this stage, then ladle more mousse on top.
Repeat this with even layers of mousse and cake until you use up your final cake layer. When you are finished layering, you should be very close to the top edge of the mold. Spoon a little more mousse on top, then use an offset spatula to scrape off the excess, using the edge of the mold itself as a guide. You should end up with a flat surface (this will be the bottom!).
Once the cake is built, it needs to be chilled so the mousse can thoroughly set. This can be done in the refrigerator or the freezer, but I like to do it in the freezer because it’s faster and it makes unfolding easier. If you let the cake freeze, you’ll need to let it thaw again before you can actually serve it, so if you’re serving it the same day as you make it, you may want to go the fridge route.
When the cake is thoroughly chilled, it’s time to unmold. If you’re using a metal mold, time to break out the kitchen torch!
Torch the sides of the mold all the way around. This helps warm (only a little bit!) the outside of the mousse, so that once the ring is warmed, you can slide it off. Depending on how long you used the torch, the mold may be hot, so use a towel if you need to! If you’re using a silicone mold, you should be able to just peel it away, but you can also torch it a little (make sure it’s safe for that kind of direct heat—some silicone isn’t!).
Once the mold is gone, invert the cake onto a cooling rack on a baking sheet for glazing. You can use the wax/parchment paper to help you with this inversion; if the cake is frozen, it’s super easy. When the cake is inverted, peel the paper away and discard.
When the cake is standing upright, it’s time to glaze. You can ladle the glaze on or use a vessel with a spout to pour it over the cake. I like to start in the center, then work in circles until I reach the edges of the cake. The excess glaze should fall easily down the sides, but you can give the surface of the cake a quick swipe with an offset spatula to help even things out. Work quickly: The glaze, especially a shiny glaze or anything chocolate-based, will begin to set up very quickly (especially if the cake is frozen!), so just go for it!
If you want to apply any decor, like sprinkles, do it before the glaze is set so it will stick. Let the glaze set for a few moments (the excess will finish running off), then use an offset spatula to transfer the cake to a platter or cake stand for serving.
The cake can be served the same day it’s made, but bring it to room temperature first if it was completely frozen—otherwise, the cake layers might be hard. If you’re not serving it the same day, refrigerate the whole cake for up to 2 days before slicing and serving!
- One recipe Sour Cream Sponge Cake (https://food52.com/recipes/52963-sour-cream-sponge-cake)
- 2.00 ounces (1/4 cup) cool water
- 0.45 ounces (1 tablespoon) granulated gelatin
- 4.50 ounces (from about about 9 large eggs) egg yolks
- 7.00 ounces (1 cup) sugar, divided
- 6.00 ounces (3/4 cup) heavy cream
- 7.50 ounces (about 1 1/4 cup) chopped dark chocolate (I used 60%), melted and cooled slightly
- 9.00 ounces (from about 8 large eggs) egg whites
- 1.00 ounce (2 tablespoons) cool water
- 0.25 ounces (2 teaspoons/1 envelope) granulated gelatin
- 3.50 ounces (1/2 cup) sugar
- 0.75 ounces (1/4 cup) dark cocoa powder
- 0.25 ounces (1 tablespoon) espresso powder (optional)
- 4.00 ounces (1/2 cup) heavy cream
- Chocolate sprinkles, for finishing (optional)
Okay, go wild—chocolate cake with raspberry mousse? Pumpkin cake with vanilla mousse? Tell us your dream cake in the comments.