Lemon Blueberry Shortbread Mousse Cake

Preheat oven to 350°F (175°C). Grease a 9-inch springform pan.
In a mixing bowl, beat softened butter and powdered sugar until creamy. Add vanilla, flour, and salt. Mix until a soft dough forms.
Press the dough into the pan and bake for 18–20 minutes, until lightly golden. Let cool completely.
In a separate bowl, whip cold heavy cream until soft peaks form. Set aside.
In another bowl, beat cream cheese, powdered sugar, lemon juice, lemon zest, and vanilla until smooth.
Gently fold the whipped cream into the lemon mixture until fluffy and well combined.
Spread the lemon mousse evenly over the cooled crust. Chill for 30 minutes.
For the blueberry topping, heat blueberries, granulated sugar, and lemon juice in a saucepan until the berries begin to burst.
Add the cornstarch slurry and simmer for 2 minutes until thickened. Allow to cool completely.
Spread the cooled blueberry topping over the mousse layer. Refrigerate for at least 2 more hours before serving.