01 - Preheat oven to 350°F. Line bottom of 9-inch springform pan with parchment paper.
02 - Beat eggs and sugar with electric mixer until pale and tripled in volume, about 5 minutes. Gently fold in flour, salt, and vanilla until just combined. Pour into pan and bake 12-15 minutes until toothpick comes out clean. Cool completely.
03 - Sprinkle gelatin over 3 tbsp cold water, let bloom 5 minutes. Heat gently until dissolved, do not boil.
04 - Blend mango puree, sugar, and lemon juice until smooth. Stir in dissolved gelatin.
05 - Whip heavy cream to soft peaks. Gently fold whipped cream into mango mixture until smooth and uniform.
06 - Pour mousse over cooled sponge base, smooth top. Refrigerate at least 2 hours until fully set.
07 - Bloom gelatin in 2 tbsp cold water for 5 minutes. Heat until dissolved. Mix mango puree, lemon juice, and sugar, stir in dissolved gelatin. Cool to room temperature.
08 - Pour cooled glaze over set mousse layer. Refrigerate at least 2 more hours until glaze is firm.
09 - Run knife around pan edge to release cake. Decorate with fresh mango slices and mint leaves if desired. Slice and serve chilled.