Lemon Blueberry Shortbread Mousse Cake

My aunt brought this to our Fourth of July gathering last summer, and I honestly could not stop thinking about it for weeks. The way the bright lemon cut through that creamy mousse, plus those jewel toned blueberry swirls, was absolute perfection on a sweltering afternoon.

I made this for my book club meeting and honestly, the whole conversation just stopped when I brought it out. Watching people take that first bite and seeing their eyes light up is exactly why I love sharing recipes like this.

Ingredients

• 1 1/2 cups all purpose flour: Forms the foundation of our buttery shortbread crust
• 1/2 cup powdered sugar: Creates a tender, melt in your mouth texture in the crust
• 1/2 cup unsalted butter, cold and cubed: Essential for that perfect shortbread crumb
• Pinch of salt: Balances sweetness and enhances flavor depth
• 1 cup heavy cream: Whips into clouds that make the mousse impossibly light
• 1/2 cup granulated sugar: Sweetens the mousse without overpowering the lemon
• Zest of 2 lemons: Those fragrant oils are where the real lemon magic lives
• 1/2 cup fresh lemon juice: Provides the bright tang that makes this dessert sing
• 1 tablespoon gelatin powder: Gives the mousse structure while keeping it silky
• 2 tablespoons water: Blooms the gelatin for seamless incorporation
• 8 ounces cream cheese, softened: Adds richness and helps the mousse hold its shape
• 2 cups fresh blueberries: Burst with juice to create that stunning compote swirl
• 1/4 cup granulated sugar: Sweetens the berries just enough to let them shine
• 1 tablespoon fresh lemon juice: Brightens the blueberry flavor beautifully

Instructions

Preheat and prep your pan:

Set your oven to 350°F and line an 8 inch springform pan with parchment paper for easy release later.

Build the shortbread crust:

Pulse flour, powdered sugar, cold butter, and salt in a food processor until you see coarse crumbs, then press firmly into your pan bottom.

Bake until golden:

Let the crust bake for 20 to 25 minutes until it smells like butter and turns golden, then cool completely.

Make the blueberry swirl:

Combine blueberries, 1/4 cup sugar, and 1 tablespoon lemon juice in a saucepan over medium heat, stirring until berries burst and thicken.

Bloom the gelatin:

Sprinkle gelatin over 2 tablespoons water in a small bowl and let it sit for 5 minutes to hydrate.

Dissolve the gelatin:

Warm the lemon juice with the bloomed gelatin, stirring gently until completely dissolved, then cool to room temperature.

Whip the creamy base:

Beat cream cheese, 1/2 cup granulated sugar, and lemon zest until completely smooth and airy.

Whip the cream:

In a separate bowl, whip that heavy cream until stiff peaks form and you can turn the bowl upside down without movement.

Bring it all together:

Beat the cooled gelatin mixture into the cream cheese base, then fold in the whipped cream with a light hand until no white streaks remain.

Layer and swirl:

Spread half the mousse over your cooled crust, spoon half the compote on top and swirl gently, then repeat with remaining layers.

Chill until set:

Refrigerate for at least 4 hours or overnight until firm enough to slice cleanly.

Serve and enjoy:

Release the springform ring, slice into wedges, and top with fresh berries if you are feeling fancy.

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This has become my go to for summer birthdays because it feels so special without heating up the kitchen. Last time I made it, my cousin actually asked if she could take the leftovers home, which is the highest compliment in my family.

Making It Your Own

Swap in raspberries or blackberries when blueberries are not in season. The technique stays exactly the same, but you get a completely different gorgeous color palette.

Perfect Presentation

Run a thin knife under hot water before slicing for the cleanest cuts. I also like to release the springform ring just before serving so the sides look perfectly smooth.

Timing Is Everything

You can make the crust and compote a day ahead, then whip up the mousse the morning you need it. This breaks up the work and makes the whole process feel completely manageable.

• Chill your bowl and beaters for 5 minutes before whipping cream
• Room temperature cream cheese blends much smoother than cold
• Plan at least 4 hours for the final chill, overnight is even better

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There is something so satisfying about serving a dessert that looks this impressive and tastes even better. Enjoy every bright, creamy bite.

Recipe FAQs

→ Can I make this dessert ahead of time?

This actually improves when made ahead. The mousse needs at least 4 hours to set properly, but you can prepare it up to 24 hours in advance. Store it covered in the refrigerator, and add any fresh garnishes just before serving.

→ How do I know when the gelatin is properly bloomed?

Sprinkle the gelatin powder over cold water and let it sit undisturbed for 5 minutes. It will absorb the liquid and become soft and wrinkled. This ensures it will dissolve smoothly when heated and properly set your mousse.

→ Can I use frozen blueberries instead of fresh?

Frozen blueberries work perfectly for the compote. No need to thaw them first—just add them directly to the saucepan. They may release more liquid than fresh, so cook for a few extra minutes until the mixture thickens nicely.

→ Why did my mousse not set properly?

This usually happens if the gelatin mixture was too hot when added to the cream cheese, or if it wasn't fully dissolved. Make sure the gelatin mixture cools to room temperature before incorporating, and heat it just until dissolved, not boiling.

→ Can I substitute the gelatin?

For vegetarians, agar-agar can replace gelatin—use about 1 teaspoon powdered agar-agar dissolved in hot liquid. Note that the texture may be slightly firmer. Alternatively, you could make a lemon curd layer instead of mousse, though the texture will differ.

→ What's the best way to get clean slices?

Use a sharp knife dipped in hot water and wiped clean between cuts. Run the knife around the edge of the pan first to release any sticking, then slice through smoothly. Chilling thoroughly for at least 4 hours, preferably overnight, ensures clean cuts.