Best Lemon White Chocolate Mousse Cake

Here is my favorite lemon white chocolate mousse cake recipe, with a light, creamy texture and a perfect balance of tart lemon and sweet white chocolate, all sitting on a simple butter cookie base.

This dessert has become my go-to choice for spring gatherings and birthday celebrations. I often make an extra one to keep in the fridge because it disappears so quickly at parties. Nothing beats a slice of this refreshing cake on a warm afternoon, don’t you think?

What Kind of White Chocolate Should I Use?

For mousse recipes, it’s important to use real white chocolate that contains cocoa butter, not the candy coating or “white baking chips” you might find at the store. Check the ingredients list – the first few items should include cocoa butter, not palm oils or other substitutes. Good quality white chocolate bars from brands like Ghirardelli, Lindt, or Callebaut will melt smoothly and give your mousse the right texture. If you’re chopping the chocolate yourself, aim for small, even pieces about the size of chocolate chips to ensure it melts evenly when combined with the warm cream. Just remember to keep white chocolate away from any water droplets while melting, as it can seize up quickly.

Options for Substitutions

Need to make some swaps? Here are some helpful substitutions for this cake recipe:

• Meyer lemon: If Meyer lemons aren’t available, use regular lemons instead. Since Meyer lemons are naturally sweeter, you might want to add an extra tablespoon of sugar to balance the tartness of regular lemons.
• Buttermilk: No buttermilk? Mix 1/4 cup regular milk with 3/4 teaspoon lemon juice or white vinegar. Let it sit for 5 minutes before using.
• White chocolate: White chocolate is key for this mousse, so I don’t recommend substituting it. Make sure to use real white chocolate (with cocoa butter) not candy melts for the best results.
• Heavy cream: Heavy cream is necessary for the mousse texture – light cream or half-and-half won’t whip properly, so try to stick with heavy cream here.
• Almond flavoring: You can skip this or replace it with vanilla extract if you prefer. The amount stays the same.
• Icing sugar: Also called powdered sugar or confectioner’s sugar. In a pinch, blend regular sugar in a food processor until very fine.

Watch Out for These Mistakes While Baking

The success of this mousse cake heavily depends on temperature control – using cold ingredients for the cake batter can lead to uneven mixing and a dense texture, so make sure your butter, eggs, and buttermilk are truly at room temperature before starting. When melting the white chocolate, avoid direct heat or microwave on high power, as it can easily seize or become grainy – instead, use a double boiler or microwave in 15-second intervals at 50% power, stirring between each interval. For the mousse layer, a common mistake is overwhipping the cream, which can turn it grainy or buttery – stop whipping as soon as stiff peaks form, and fold in the melted (but cooled) white chocolate gently to maintain the airy texture. To prevent the cake from drying out while setting, make sure to cover it properly in the refrigerator, and let it sit at room temperature for 15-20 minutes before serving to allow the flavors to fully develop.

What to Serve With Lemon Mousse Cake?

This light and refreshing dessert pairs wonderfully with a hot cup of Earl Grey tea or a smooth cappuccino, as the citrus notes complement the bergamot in the tea and the coffee’s richness. If you’re serving this cake for a summer dessert, try adding a scoop of fresh raspberry sorbet on the side – the tartness of the berries works really well with the sweet white chocolate and zingy lemon flavors. For a simple but tasty addition, you could also serve it with a dollop of lightly sweetened whipped cream and a handful of fresh mixed berries scattered around the plate.

Storage Instructions

Keep Chilled: This lemon white chocolate mousse cake needs to stay cool to maintain its dreamy texture. Pop it in the fridge in an airtight container, and it’ll stay fresh for up to 3 days. The mousse layer will hold its shape best when kept cold!

Make Ahead: You can prepare this cake a day before your special event. In fact, letting it chill overnight helps the flavors blend together nicely and makes the mousse extra firm. Just add the lemon garnish right before serving to keep it looking fresh.

Not Suitable for Freezing: I don’t recommend freezing this cake as the mousse texture can become grainy when thawed, and the whipped cream might separate. It’s best enjoyed within a few days of making while the layers are still perfect and fresh.

Preparation Time	30-45 minutes
Cooking Time	30-35 minutes
Total Time	120-135 minutes
Level of Difficulty	Medium

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 2200-2400
• Protein: 20-25 g
• Fat: 150-160 g
• Carbohydrates: 200-230 g

Ingredients

• 3/4 cup plain flour
• 1/8 teaspoon salt
• 1/4 teaspoon baking soda
• 6 tablespoons room temperature unsalted butter
• 1/2 cup white sugar
• Zest and juice of 1 meyer lemon
• 1/8 teaspoon almond flavoring
• 1 large egg, at room temperature
• 1/4 cup buttermilk
• 1 cup heavy cream, separated
• 2 ounces chopped white chocolate
• 1 tablespoon icing sugar
• 1 lemon, thinly sliced for garnish

Step 1: Prepare the Baking Pan and Oven

Preheat your oven to 350 degrees F.

Grease and line a 6-inch round pan with parchment paper, making sure to also grease the parchment to prevent the cake from sticking.

Step 2: Mix Dry and Wet Ingredients

In a small bowl, whisk together the flour, salt, and baking soda.

In the bowl of an electric mixer, cream the butter and sugar together on medium speed until pale and fluffy, about 2-3 minutes.

Then, add in the lemon zest, lemon juice, almond extract, and egg, beating until just combined.

Step 3: Combine Ingredients to Form Batter

Reduce the mixer speed to low and slowly add one-third of the flour mixture to the batter, followed by 2 tablespoons of buttermilk.

Beat until just combined.

Add another third of the flour mixture and mix, followed by the remaining buttermilk, then the final third of the flour.

Scrape down the sides of the bowl as needed, taking care not to overmix.

Step 4: Bake the Cake

Transfer the prepared batter into the greased and lined pan.

Bake in the preheated oven until the cake is lightly golden and a toothpick inserted into the center comes out clean, approximately 30-35 minutes.

Remove from the oven and allow the cake to cool in the pan for at least 10 minutes before carefully turning it out onto a cooling rack.

Step 5: Prepare the Mousse Frosting

Place a medium-sized bowl and whisk beaters in the freezer to chill for at least 10 minutes.

In the meantime, combine the chocolate and 1/4 cup heavy cream in a small heatproof bowl and microwave for 30 seconds until the cream starts boiling.

Let it sit for at least 2 minutes without stirring.

Step 6: Whisk the Mousse and Decorate the Cake

Remove the chilled bowl from the freezer and pour in the remaining heavy cream.

Using an electric mixer, beat the cream until soft peaks form.

Add the powdered sugar and continue beating until combined.

Whisk the melted chocolate and cream until smooth, then slowly pour it into the whipped cream mixture while beating continuously until fully incorporated.

Step 7: Frost and Set the Cake

Use the mousse frosting to generously frost the cooled cake.

Cover the frosted cake and refrigerate it for at least two hours to allow the mousse to set.

Before serving, top with lemon slices for a decorative touch and added flavor.