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