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
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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.
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Equipment
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My son and his family have come and gone. They called to say what a wonderful visit they had and are still raving about this wonderful cake. I had to bake it 3 times to get it right,, It was a fabulous showstopper. I learned so much. I also made the homemade marshmallows. I changed the flavoring to almond for my daughter in law. These were a real hit. I love tis web site.I am going to look for my next culinary adventure from Eileen’s recipes.
Well, thanks Suzanne. I’m so glad you’re having fun trying the recipes.
I am not much of a baker.Rarely ever making a cake from scratch. But this cake recipe has all the bells and whistles to to make me think it comes directly from heaven. I have now attempted to make it 3 times. And failed 3 times. It tastes ok but the layers do not raise more 2 inches each. I first made it in 9 inch pans. And thought maybe the learners were old so bought new baking soda and baking powder and again did not raise more than 2 inches. The third time I bought new 8 inch pans and did not grease the sides as I had previously. I thought this will be it!!!!!!Wrong……Still to flat to slice to make 4 layers. This time I was so sure I would succeed that I made the syrup with the limoncello, the lemon curd and attempted the Italian Meringue buttercream. The curd and syrup are good The buttercream not so much. The consistency does not feel right. My kids are coming from out of state and I wanted the perfect cake…….I have tomorrow to make a final attempt…….
help
Hi Suzanne, It’s hard to tell what’s happening without knowing every single detail of how you made the cakes. I’ve been making this recipe for more than 10 years and it always rises for me. But, when you split the cakes each layer will be just 1″-1 1/2″ tall. I do that purposely because I prefer 4 thinner layers to 2 thicker layers. I like to have more filling:cake ratio, if you get what I mean. You can see how thin each layer is in the video. Italian Meringue Buttercream should be light and fluffy, but it is less sweet and more buttery than American buttercream or canned buttercream. Not sure if there was a problem with making the buttercream or maybe it’s a different consistency than you’re used to. Sorry I can’t help more. If you have other specific questions I’d be happy to answer. Eileen
Oh. My. Yum! I made this cake for Easter and it was a hit. Not something you want to make on the fly, but totally worth the effort. I couldn’t find Limencello so I’ll be keeping an eye out for some or maybe give making it from scratch a go. Thank you for sharing your recipe!
So glad you liked it, Elizabeth. It’s been a favorite for years. If you can’t find limoncello, try using a little vodka with lemon zest.
Can you make the mouse the night before and store it in the fridge?
Thanks,
Kim
And if I make it the night before can I put it in a piping bag to help put it on the cake evenly?
Thanks again!
Sure, that might make it easier. Just use a large tip. Just don’t forget the buttercream dam to keep the mousse in.
I used a piping bag and it worked really well.
Hi Kim. You can make the mousse ahead, but the gelatin in the mousse will set up in the refrigerator. It will be a little more difficult to spread it on the layers. Pipe the dam of buttercream as described in the recipe and scoop the mousse onto the layer. You’ll have to squish the mousse into place a bit since it won’t be soft and flowy, as it is in the video. If you are making all the components the night before it might be just as easy to assemble the cake the day before as well. It will hold up for several days in the refrigerator. Please let me know if you have any other questions.
How generous are you with brushing on the syrup? Do you soak the cake through?
Hi Alexi – Since this isn’t a sponge cake you don’t want to completely soak the cake. A butter cake won’t absorb the syrup the way a sponge cake will and if it gets too wet it will become gummy. For the Luscious Lemon Mousse Cake the syrup is there more for flavor than for moistness. You want to use up the amount of syrup listed in the recipe. That means for each layer you’ll brush 1/4 of the syrup. Enjoy!