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, about 5 to 7 minutes. Remove from heat and whisk in butter until smooth. Transfer to a bowl and let 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 to 7 minutes. Let cool completely.
03 - In a chilled mixing bowl, whip heavy cream with powdered sugar and vanilla extract until soft peaks form using an electric mixer or hand whisk.
04 - Gently fold cooled lemon curd into whipped cream until fully combined and smooth, using a rubber spatula to maintain airiness.
05 - Spoon a layer of blueberry compote into the bottom of 4 serving glasses. Top with lemon mousse. Repeat layers if desired, finishing with mousse on top.
06 - Refrigerate assembled mousse for at least 2 hours to set. Garnish with fresh blueberries, lemon zest, and mint leaves before serving.