01 - Preheat the oven to 350°F. Line the bottom of a 9-inch springform pan with parchment paper.
02 - Beat eggs and sugar with an electric mixer until pale and tripled in volume (about 5 minutes). Gently fold in flour, salt, and vanilla extract until just combined. Pour into the pan and bake for 12-15 minutes, or until a toothpick inserted in the center comes out clean. Cool completely in the pan.
03 - Sprinkle gelatin over 3 tbsp cold water and let bloom for 5 minutes. Gently heat bloomed gelatin 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 the mango mixture until smooth.
05 - Pour the mousse over the cooled sponge base, smoothing the top. Refrigerate for at least 2 hours until set.
06 - Bloom gelatin in 2 tbsp cold water. Gently heat until dissolved.
07 - Mix mango puree, lemon juice, and sugar in a bowl, then stir in dissolved gelatin. Let cool to room temperature, then pour over the set mousse layer.
08 - Chill for at least 2 more hours, or until the glaze is firm. Carefully run a knife around the edge of the pan and remove the cake. Decorate with fresh mango slices and mint leaves if desired. Slice and serve chilled.