Preheat & Prep

Preheat your oven to 350°F (175°C). In a mixing bowl, combine 1 cup of all-purpose flour, 1/4 cup of granulated sugar, and 1/2 cup of softened unsalted butter. Mix until the mixture is crumbly. Press this mixture firmly into the bottom of a baking dish, ensuring an even layer. Bake for 15 minutes or until golden brown. Once baked, allow it to cool completely. This shortbread crust serves as the perfect crisp base for your cake.

Make the Lemon Mousse

In a small pot, mix together 1/2 cup of freshly squeezed lemon juice, 1 tablespoon of lemon zest, 1/2 cup of granulated sugar, and 1 tablespoon of gelatin. Place the pot over low heat, stirring until the gelatin is fully dissolved. Remove from heat and allow it to cool slightly. In a separate bowl, whip 1 cup of heavy cream until soft peaks form. Gently fold the cooled lemon mixture into the whipped cream. Finally, sprinkle in 1/2 cup of blueberries, folding them in gently to maintain their shape.

Create the Blueberry Topping

In another medium-sized pan, combine 1 cup of blueberries, 1 tablespoon of cornstarch, 1/4 cup of granulated sugar, and 1/4 cup of water. Cook the mixture over medium heat, stirring occasionally, until it thickens and becomes glossy. Once thickened, remove from heat and set it aside to cool.

Assemble the Cake

Carefully pour the lemon mousse over the cooled shortbread crust, using a spatula to smooth it out evenly across the surface. Then, top the mousse layer with the cooled blueberry mixture, spreading it to cover the mousse entirely. This vibrant topping adds an eye-catching finish to your cake.

Chill & Serve

Refrigerate the cake for at least 4 hours or until it is set. Once fully chilled, slice it into pieces, serve, and enjoy the delightful reactions from family and friends as they indulge in this refreshing dessert.