Prepare the Shortbread Crust

• Preheat your oven to 350°F (175°C). In a mixing bowl, cream together the softened butter and sugar until light and fluffy. Gradually add the flour and salt, mixing until a dough forms.

Bake the Crust

• Press the dough into the bottom of a 9-inch springform pan evenly. Bake for 20-25 minutes or until lightly golden. Remove from the oven and let it cool completely.

Make the Lemon Mousse

• In a small bowl, sprinkle gelatin over cold water and let it sit for 5 minutes to bloom. In a saucepan, combine lemon juice, lemon zest, and sugar over medium heat. Stir until the sugar dissolves. Remove from heat and add the bloomed gelatin, stirring until dissolved.

Whip the Cream

• In a separate mixing bowl, whip the heavy cream until soft peaks form. Gradually fold the lemon mixture into the whipped cream until fully combined.

Assemble the Cake

• Pour the lemon mousse over the cooled shortbread crust and smooth the top. Refrigerate for at least 2 hours or until the mousse is set.

Prepare the Blueberry Compote

• In a saucepan over medium heat, combine the blueberries, sugar, lemon juice, cornstarch, and water. Cook for 5-7 minutes, stirring gently until the blueberries release their juices and the mixture thickens. Remove from heat and let it cool.

Top the Cake

• Once the mousse is set, pour the cooled blueberry compote over the top of the cake, spreading it evenly. Refrigerate for an additional hour before serving.

Serve the Cake

• Carefully remove the sides of the springform pan. Slice and serve chilled, garnished with extra blueberries or lemon zest if desired.