01 - Preheat the oven to 320°F. Line the base of a 9-inch springform pan with parchment paper.
02 - Crush biscuits into fine crumbs. Mix with melted butter and sugar. Press firmly into the pan base. Bake for 10 minutes, then cool completely.
03 - Beat cream cheese and sugar until smooth. Add eggs one at a time, mixing gently. Blend in vanilla, sour cream, and flour until just combined.
04 - Pour filling over cooled crust. Bake for 45-50 minutes until edges are set but center is slightly wobbly. Turn off oven, crack door, and cool for 1 hour. Remove and refrigerate for 2 hours.
05 - Combine blueberries, sugar, and lemon juice in a saucepan. Cook over medium heat for 5-7 minutes until berries burst. Purée, then strain to remove seeds.
06 - Sprinkle gelatin over water and let bloom for 5 minutes. Warm gently until dissolved. Stir into warm blueberry purée. Cool to room temperature.
07 - Whip heavy cream to stiff peaks. Gently fold in cooled blueberry mixture until smooth and airy.
08 - Spread mousse evenly over chilled cheesecake. Refrigerate for at least 2 hours until completely set.
09 - Top with fresh blueberries and mint leaves before serving.