Easy Lemon Blueberry Mousse Cake with Buttery Shortbread

There’s something magical about the bright, zesty flavor of lemons paired with the sweet burst of blueberries. Now imagine all of that goodness nestled on a buttery, crumbly shortbread crust and topped with a silky smooth mousse. That’s what this Easy Lemon Blueberry Mousse Cake is all about—a show-stopping dessert that’s light, fresh, and absolutely irresistible. Whether you’re celebrating a special occasion or just craving something fruity and creamy, this no-fuss mousse cake is going to be your new go-to.

You’ll love how easy this is! Despite its elegant look, this dessert comes together with simple ingredients and minimal effort. The result? A bakery-worthy cake that’ll impress every single time.

Ingredients
(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

For the Shortbread Crust:
This base is what gives the cake its rich, buttery bite—an absolute dream.

• Unsalted butter: Softened, not melted. This helps keep the dough tender.
• Powdered sugar: For that delicate sweetness and smooth texture.
• All-purpose flour: Gives structure to the crust.
• Salt: Just a pinch to balance the sweetness.
• Vanilla extract: Adds a subtle warmth to the shortbread.

For the Lemon Mousse:
Bright and creamy, this lemon mousse is a balance of tart and sweet.

• Heavy whipping cream: Cold and whipped to soft peaks for fluffiness.
• Cream cheese: Softened so it blends seamlessly into the mousse.
• Powdered sugar: Keeps the mousse smooth and sweet.
• Fresh lemon juice: Go for freshly squeezed—it makes a big difference.
• Lemon zest: Adds intense citrus aroma and flavor.
• Vanilla extract: Adds a gentle note that complements the lemon.

For the Blueberry Topping:
Sweet and juicy, this topping adds a fruity burst and vibrant color.

• Blueberries: Fresh or frozen both work. Don’t thaw frozen ones!
• Granulated sugar: Just enough to bring out the berries’ natural sweetness.
• Lemon juice: Brightens up the berry flavor.
• Cornstarch + water: Thickens the sauce just enough to sit perfectly atop the mousse.

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Instructions

Make the Shortbread Crust

1. Preheat and Prep: Start by preheating your oven to 350°F (175°C). Grease a 9-inch springform pan or line the bottom with parchment paper for easy removal.
2. Mix the Dough: In a large mixing bowl, beat the softened butter and powdered sugar until creamy and smooth. Add vanilla, then stir in the flour and salt. The dough will be soft and slightly crumbly—don’t worry, that’s perfect!
3. Form and Bake: Press the dough evenly into the bottom of the pan, making sure to get into the corners. Bake for 18–20 minutes or until the edges are lightly golden. Set aside to cool completely before adding any layers.

Make the Lemon Mousse

1. Whip the Cream: In a cold bowl, whip the heavy cream to soft peaks. Set it aside in the fridge while you prepare the rest.
2. Creamy Base: In another bowl, beat the cream cheese with powdered sugar, lemon juice, zest, and vanilla until silky smooth and lump-free.
3. Combine: Gently fold the whipped cream into the lemon mixture using a spatula. Work in batches, folding until fully combined but still airy. You’ll end up with a light, luscious mousse that holds its shape beautifully.
4. Layer It On: Spread the lemon mousse over the cooled shortbread crust, smoothing the top with a spatula. Place the cake in the refrigerator and let it chill for at least 30 minutes while you make the blueberry topping.

Make the Blueberry Topping

1. Cook the Berries: In a small saucepan, combine blueberries, sugar, and lemon juice. Cook over medium heat, stirring occasionally, until the berries begin to break down and release their juices (about 5–7 minutes).
2. Thicken the Sauce: Stir in the cornstarch slurry (cornstarch mixed with water) and simmer for another 1–2 minutes until the mixture thickens slightly. Remove from heat and let cool completely.
3. Top the Cake: Once the blueberry mixture has cooled, gently spoon it over the set lemon mousse. Spread evenly with a spatula.

Assemble & Chill

1. Final Chill: Place the fully assembled cake in the refrigerator for at least 2 hours (overnight is best). This gives the mousse time to firm up and the flavors to meld together.
2. Serve: When you’re ready to serve, run a knife around the edges of the springform pan and release it. Slice with a sharp knife for clean, beautiful pieces.

Tips and Tricks

• Use cold ingredients for the mousse: This helps everything whip up better and hold its shape longer.
• Room temperature cream cheese: Prevents lumps in your mousse—nobody wants chunks!
• Zest before juicing: Always zest your lemon first; it’s nearly impossible once the lemon is juiced.
• Clean cuts: Dip your knife in hot water and wipe dry between each slice for picture-perfect pieces.
• Make ahead: This cake is ideal for prepping the night before. The flavors deepen as it rests.

Serving Suggestions

• Garnish Ideas: Top with fresh blueberries, a few lemon curls, or even a sprig of mint to make it pop.
• Pair it up: Serve with a cup of Earl Grey tea or a glass of cold lemonade for a fresh, summery dessert moment.
• Small slices, big flavor: This dessert is rich yet light—perfect for smaller portions that still satisfy.

Storage Instructions

• Refrigerate: Always keep the cake chilled due to the mousse layer. It stays fresh for up to 3 days when covered properly.
• Cover loosely: Use a cake dome or plastic wrap to keep moisture in and fridge odors out.
• Freezing not recommended: The mousse might separate or become grainy once thawed. For best results, enjoy it fresh from the fridge.

Possible Variations

• Switch the berries: Try raspberries or blackberries for a different twist.
• Add lemon curd: For an extra punch of citrus, layer lemon curd between the mousse and blueberry topping.
• Try mini versions: Make individual servings in small ramekins or jars—great for dinner parties or gifting!

Frequently Asked Questions

Can I make this cake ahead of time?
Absolutely! In fact, it tastes even better after a night in the fridge. Just assemble everything, chill, and serve the next day.

What if I don’t have fresh blueberries?
No problem! Frozen blueberries work great—just cook them a bit longer to account for the extra moisture they release.

Can I make it vegetarian?
This version uses no gelatin, so it’s naturally vegetarian-friendly. If you’re tweaking it to include gelatin, substitute with agar-agar for a plant-based option.

How do I know the mousse is set?
The mousse should feel firm but slightly jiggly when touched. If it’s still loose, give it more time in the fridge.

Final Thoughts

This Lemon Blueberry Mousse Cake is a celebration of everything light, bright, and beautiful. The buttery shortbread crust melts in your mouth, the lemon mousse is airy yet decadent, and the blueberry topping gives the perfect fruity finish. It’s easy enough for a weekend treat and impressive enough for any special occasion.

Once you try it, it’ll quickly become a staple in your dessert rotation. Enjoy every refreshing bite!