01 - Whisk together lemon juice, lemon zest, sugar, and egg yolks in a small saucepan. Place over medium-low heat and cook, stirring constantly, until mixture thickens and coats the back of a spoon, approximately 5–7 minutes. Remove from heat and whisk in cubed butter until completely smooth. Transfer to a clean bowl and allow to cool completely.
02 - Combine blueberries, sugar, and lemon juice in a small saucepan. Cook over medium heat, stirring occasionally, until blueberries burst and sauce thickens slightly, about 5–7 minutes. Remove from heat and allow to cool completely.
03 - In a chilled mixing bowl, whip the cold heavy cream with powdered sugar and vanilla extract using an electric mixer or hand whisk until soft peaks form.
04 - Gently fold the completely cooled lemon curd into the whipped cream using a rubber spatula, incorporating until fully combined and smooth. Take care not to deflate the mixture.
05 - Spoon a layer of cooled blueberry compote into the bottom of 4 serving glasses. Top with lemon mousse mixture. Repeat layers if desired, ensuring mousse is the final top layer.
06 - Refrigerate assembled mousses for at least 2 hours to set completely. Before serving, garnish with fresh blueberries, additional lemon zest, and mint leaves if desired.