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 prepared pan and bake 12-15 minutes until toothpick comes out clean. Cool completely in pan.
03 - Sprinkle gelatin over 3 tablespoons cold water and let bloom 5 minutes. Gently heat until dissolved, do not boil.
04 - Blend mango puree, sugar, and lemon juice until smooth. Stir in dissolved gelatin. Whip heavy cream to soft peaks and gently fold into mango mixture until smooth.
05 - Pour mousse over cooled sponge base, smoothing top. Refrigerate at least 2 hours until set.
06 - Bloom gelatin in 2 tablespoons cold water. Gently heat until dissolved.
07 - Mix mango puree, lemon juice, and sugar in bowl, then stir in dissolved gelatin. Let cool to room temperature.
08 - Pour glaze over set mousse layer. Chill at least 2 more hours until glaze is firm.
09 - Run knife around edge of pan and remove cake. Decorate with fresh mango slices and mint leaves if desired. Slice and serve chilled.