Luscious Lemon Mousse Cake
This Luscious Lemon Mousse Cake might be the perfect layer cake. Buttery lemon cake with Limoncello syrup, zesty lemon curd and creamy lemon mousse. (Liquor is optional.)
Table of contents
About this recipe
I am so excited to share this recipe with you! This was the most popular cake flavor for my custom cake business. Once I introduced the Chocolate Chip Cookie Cake the two cake flavors shared top billing.
This cake is truly luscious. Yes, it is a bit of a project. But I think it’s totally worth the effort, especially for a special occasion.
Because it’s most efficient to break this recipe down into the individual components, I have structured the post this way. Use the table of contents to jump to the section for the individual component you’re working on.
Once you have all the components made, jump to the section that shows how to put it all together.
Watch the video and scroll through the photos to see the entire process. You can see how easily the whole thing comes together once you have all the components in place.
Of course, if you’ve already made this recipe or are a very confident baker, jump straight to the recipe card and you’ll find all the information you need to make this cake.
Ingredients
Cake Ingredients
Ingredient Note: I prefer to use bleached cake flour for the softest cake. Unbleached cake flour is fine to use. As a last option, use all purpose flour to make the cake flour substitute in this post.
Curd & Mousse Ingredients
Ingredient Notes:
- Use the gelatin when you make the lemon curd. The gelatin keeps the curd from running out of the layers when the cake is cut.
- If you can’t or don’t want to do liquor you can use water to bloom the gelatin and lemon juice to flavor the syrup. The limoncello adds a deep lemon flavor without leaving a boozy aftertaste. You can check out this post to see why alcohol enhances flavor.
Buttercream Ingredients
Ingredient Note: If you use carton egg whites make sure the label says they can be used for making meringue. Not all carton whites are appropriate for whipping.
Process Photos
See the recipe card for detailed measurements and instructions.
Cake
Visit this vanilla cake post to see detailed step by step photos for making the cake layers. Use the recipe and process in that post, adding the zest with the dry ingredients and the lemon extract with the vanilla.
Frosting
Visit this Swiss Meringue Buttercream post to see detailed step by step photos for making the lemon frosting. Use the recipe and process in that post flavored with 1/4 cup Limoncello (or to taste) and/or 1 teaspoon lemon extract.
If you want to make a “Lemon Meringue” variation of this cake, you can ice the cake with Seven Minute Frosting instead of the meringue buttercream. Use a blow torch on the seven minute frosting for a lovely toasted finish.
Lemon Curd
Visit this post to see a video showing how to make the lemon curd. Use the optional gelatin listed in the recipe.
Mousse
- Combine the limoncello (or water) and lemon extract in a small microwave safe bowl. Sprinkle the gelatin over the surface and whisk to combine. Set the gelatin aside to bloom for 5 minutes.
- Fold the whipped cream into the lemon curd.
- Whisk 1 cup of the cream mixture into the melted gelatin.
- Immediately whisk the tempered gelatin into the mousse. Use immediately to assemble the cake.
Why we “liason” (aka temper) gelatin
Tempering gelatin is similar to tempering eggs into hot milk to make custard.
If you simply poured the warm gelatin into the cool mousse it might immediately set into little rubbery lumps. Definitely not the texture we’re going for here.
By whisking a scoop of mousse into the melted gelatin we bring the two ingredients closer together in texture and temperature. Once we add the tempered gelatin back into the mix we have silky-smooth mousse.
Assembly
- Trim the brown crusts off the two cakes and split them horizontally (this is called “torting”). You’ll have 4 layers. Generously brush the first layer with lemon syrup.
- Pipe a “dam” of buttercream around the edge of the layer.
- Spread half the lemon mousse onto the layer. Top with the next layer.
- Pipe a dam of buttercream on the second layer and spread lemon curd over the layer. Place the 3rd layer on the cake, pipe a dam and fill with the remaining lemon mousse.
- Place the 4th layer on the cake. Refrigerate the cake for at least 30 minutes to set the buttercream dams.
- Ice the cake with a crumb coat of buttercream. Refrigerate for 1 hour. Then ice with a final coating of buttercream.
- Pipe a border around the top of the cake.
- Fill the border with lemon curd. Refrigerate for at least 4 hours (or overnight) before slicing. Remove from the refrigerator 1/2 hour before serving to allow the buttercream to soften.
Work Ahead Schedule
Cake Layers
It’s easier to work with the cakes when they’ve had time to cool completely and for the starch to set. The baked cakes should be wrapped tightly and can be held at room temperature for 1 day. The cakes can be frozen for up to a month.
Lemon Curd
The lemon curd can be made ahead and held in the refrigerator for 2-3 days or in the freezer for up to a month. Bring the curd back to room temperature before making the mousse and assembling the cake.
Lemon Syrup
The lemon simple syrup can be held in the refrigerator for a week or frozen for a month.
Buttercream
The Swiss Meringue Buttercream can be made ahead and held at room temperature for 1 day, in the refrigerator for 2-3 days or frozen for a month. If you refrigerate or freeze the buttercream is should be brought back to room temperature and re-whipped before assembling the cake.
If you plan to use the 7 Minute Frosting that must be used to ice the cake as soon as it’s made. In this case I recommend having all components ready to go before you make the frosting. Ice the cake as soon as it’s assembled.
Lemon Mousse
The lemon mousse must be used before it has time to set. Have all the components of the cake ready to go before mixing the mousse.
Storage
Store your Lemon Mousse Cake in the refrigerator until about 1/2 – 1 hour before serving. This gives the buttercream time to soften before serving. The cake can be kept in the refrigerator for 3-4 days.
Once the cake is sliced, keep a piece of plastic wrap over the cut ends so they don’t dry out. Left over slices of cake can be wrapped in plastic and frozen for up to a month. Defrost in the plastic wrap before serving.
Want to learn more about how I create my cake recipes? This post has lots of great information about baking science and how to perfect any recipe.
More Lemon Recipes
More Layer Cakes
If you love this recipe as much as I do, I’d really appreciate a star rating and a quick comment. Ratings and comments help my recipes show in search results. Thanks!
Luscious Lemon Mousse Cake
Ingredients
Cake
- 1 recipe Vanilla Butter Cake
- 1 lemon (finely grated zest)
- 2 teaspoons lemon extract
Lemon Mousse
- 1 ½ oz Limoncello (or water for no alcohol)
- 1 teaspoon lemon extract
- 1 ½ teaspoons gelatin powder
- 8 oz heavy cream (1 cup, chilled)
- 2 tablespoons powdered sugar
- 12 oz Lemon Curd (1 ¼ cups)
Assembly
- 1 recipe Swiss Meringue Buttercream (or your favorite buttercream flavored to taste with lemon extract, lemon zest and Limoncello)
- 1 recipe Simple Syrup (flavored with ¼ cup Limoncello or 1 teaspoon lemon extract)
- 16 oz Lemon Curd (1 ¾ cups)
Instructions
Cake
- Mix the cake batter according to the recipe, adding the finely grated zest of 1 lemon to the dry ingredients and 2 teaspoons lemon extract with the vanilla.
- Divide the batter between two 8"x3" pans lined with a parchment round or buttered and floured. Bake as instructed in the recipe. Wrap the cooled layers and chill until firm (I like to bake the cake a day ahead).
- When you're ready to assemble the cake, trim the browned edges and domed top off both cakes. Split each cake horizontally so you have a total of 4 cake layers.
Have your syrup, buttercream and lemon curd ready before you begin making the Lemon Mousse.
Lemon Mousse
- Place 1 ½ oz Limoncello (or cold water) and 1 teaspoon lemon extract into a microwave safe bowl. Sprinkle 1 ½ teaspoons gelatin powder over the liquid in an even layer. Whisk briefly to combine and set aside to bloom. Whip 8 oz heavy cream with 2 tablespoons powdered sugar and set aside.
- Place the 12 oz Lemon Curd (1¼ cups) in a large mixing bowl and use a spatula to smooth out the curd to break up any lumps. Fold ⅓ of the whipped cream into the lemon curd until no lumps of curd remain. Fold in the remaining cream until it's about ½ way incorporated.
- Heat the bloomed gelatin in the microwave in 10 second increments until it's hot to the touch. Working quickly, add a ½ cup of the mousse to the warmed gelatin. Whisk immediately until completely incorporated. Pour the gelatin mixture back into the mousse. Immediately whisk until the mousse is smooth and the gelatin is evenly incorporated.
Assembly
- Fill a piping bag fitted with a star tip with buttercream (or use a disposable bag with the tip cut).
- Set one layer of the cake, flat side down, onto a cardboard cake round or a serving plate. Brush the layer generously with the Limoncello syrup. Pipe a ring of buttercream around the edge of the layer to form a "dam" for the mousse. Scoop half the lemon mousse onto the layer and smooth until even.
- Gently place the second cake layer onto the mousse, careful not to squish the mousse layer. Brush the layer with syrup and pipe a dam of buttercream. Set aside a ½ cup of the lemon curd and scoop the rest onto the layer. Smooth the curd until even (be careful not too press hard or you might squish the mousse layer beneath).
- Place the 3rd cake layer, brush with syrup and pipe a dam. Fill with the remaining lemon mousse. Top with the 4th layer, brush with syrup. Set the cake into the refrigerator for about 20 minutes to set the buttercream "dams" and the mousse.
- Ice the cake with a thin crumb coat of buttercream. Refrigerate the cake for at least an hour to set the buttercream and allow the mousse time to gel. Ice the cake with a final coating of buttercream.
- Use a piping bag fitted with a star tip to pipe a border around the top of the cake. Spread the last ½ cup of curd onto the cake. Refrigerate for at least 4 hours to make sure the filling is completely set, preferably over night.
- Remove the cake from the refrigerator ½ hour before serving.
Would you like to save this recipe?
We’ll email this post to you, so you can come back to it later!
Equipment
As an Amazon Associate and member of other affiliate programs, I earn from qualifying purchases.
Thank you for this recipe. Do you think the lemon curd can be substituted for salted caramel for a salted caramel mousse? Would the quantities need to be adjusted? Thank you.
Sorry, I don’t understand what you’re asking. Are you asking if you could put salted caramel in the cake instead of curd?
Yes, I was wondering if the lemon curd in the mousse can be substituted for salted caramel and what adjustments might be necessary. Thank you.
So you want to make a caramel mousse? The key is the base of the mousse must be thick and flavorful. So it would depend on the texture of your caramel. If it’s very thin you may need more gelatin to set the mousse so it doesn’t leak out of the cake.
I never got one of my 8″ pans back from making something for someone and I’m only now realizing this as I’m ready to (try to) make this cake! Can this be made in a differnt pan such as a bundt pan or one large pan?
A Bundt pan wouldn’t work for this recipe since you couldn’t really turn it into a layer cake. It would be possible to bake the batter in a half sheet pan then cut the half sheet into 4ths to make 4 layers. Then assemble the cake as you could with a round cake.
Hi
I have an abundance of limes. Is it possible to make this cake using limes instead>
Kerrie
NZ
Yes, just substitute with the same measurements.
You could use a Bundt pan — I used a hemisphere pan. The trick is then slicing the layers. I use a cake slicer thing with a wire — that would work or you could free hand with a knife. You could also pile mousse in the middle. You could assemble the cake back in the pan using plastic wrap layer it, refrigerate and then unmold it and cover with ganache or icing or lemon drizzle.
I’d like to do this as a filling in my son’s birthday cake! Would it work in a 6 layer cake or would that be too heavy for the mousse? Thanks
Do you plan to do the entire cake recipe as is or just use use either the mousse or curd as a filling? If you have six layers just be sure that the filling layers are fairly thin so the whole cake stays together. You want a balance of cake and filling.
I was planning on a basic lemon sponge cake with the mousse and curd filling! Thank you for your advice!
I tried baking this cake twice today. Both times the cake looked fine when I pulled it out, but sunk as soon as I did! So disappointed!
What do you mean by “sunk”? This cake can shrink a bit as it cools but if you slice it open it should be fine.