For the Italian meringue, put 55ml/2fl oz water in a pan with the sugar and glucose. Gently heat to 110C (check with a sugar thermometer) then keep a close eye on it and remove it from the heat as soon as it reaches 120C.
Meanwhile whisk the egg whites to soft peaks in a freestanding mixer. As soon as the sugar comes to 120C, slowly add it to the egg whites in a thin steady stream with the motor running all the time. Leave to mix for 15 minutes or until the bowl is cool. Set aside.
For the sponge fingers, preheat the oven to 190C/170C Fan/Gas 5. Lightly grease 3 baking trays and line them with baking paper.
Whisk the egg yolks with half the sugar until pale and the thick enough to leave trails on the surface of the batter when the whisk is removed (the ribbon stage).
In a separate bowl, whisk the egg whites with the remaining sugar and the salt until soft peaks form when the whisk is removed. Fold the egg whites into the egg yolk mixture using a metal spoon. Fold in the flour. Transfer the mixture to a piping bag attached with a large plain nozzle.
Pipe into 11cm/4in lines spaced 2.5cm/1in apart. Make a syrup by heating the sugar with 100ml/3½fl oz water. Sprinkle the syrup over the sponge fingers and bake for 10 minutes. Leave to cool on a wire rack.
For the génoise sponge, preheat the oven to 200C/180C Fan/Gas 6. Grease and line a Swiss roll tin.
Whisk the egg yolks and sugar until pale and the thick enough to leave trails on the surface of the batter when the whisk is removed (the ribbon stage). Gently fold in the sifted flour and the melted butter.
Pour the batter into the prepared tin and bake for 10 minutes, or until golden-brown and springy to touch. Set aside to cool slightly, then remove from the tin and allow to cool completely on a wire rack. Cut out 2 x 18cm/7in circles of cake.
For the raspberry bavarois, heat the milk, raspberry purée and lime juice in a large pan.
Using an electric mixer, whisk the egg yolks and sugar until pale and doubled in volume. When the raspberry mixture comes to the boil, slowly add it to the egg mixture in a thin steady steam, whisking all the time. Return the mixture to the pan and heat gently for a few minutes until thick enough to coat the back of a spoon (do not allow it to boil as it might split).
Squeeze out any excess liquid from the gelatine and stir it into the raspberry mixture until dissolved. Leave to cool.
Whip the cream until thick enough to leave trails on the surface when the whisk is removed (the ribbon stage). Add 120g/4oz of the cooled Italian meringue and mix using a silicone spatula. Stir in the raspberry mixture and chill until ready to use.
Line a 20cm/8in cake tin with cling film making sure there is plenty overhang at the sides. Place one of the discs of génoise sponge in the bottom of the tin (the cake disc needs to be smaller than the base to allow the sponge fingers to sit inside comfortably).
Trim one end of the sponge fingers so they are all the same length and will sit neatly in the tin. Place the sponge fingers around the side of the tin with a slight overlap to ensure there are no gaps (to prevent the filling leaking out). Pour in the raspberry bavarois, smooth the surface and transfer to the fridge to set (do this in the freezer if you are short of time).
For the mango bavarois, heat the milk, mango pulp and lime juice in a large pan.
Using an electric mixer, whisk the egg yolks and sugar until pale and doubled in volume. When the mango mixture comes to boil, slowly add it to the egg mixture in a thin steady steam, whisking all the time. Return the mixture to the pan and heat gently for a few minutes until thick enough to coat the back of a spoon (do not allow it to boil as it might split).
Squeeze out any excess liquid from the gelatine and stir it into the mango mixture until dissolved. Leave to cool.
Whip the cream until thick enough to leave trails on the surface when the whisk is removed (the ribbon stage). Add 120g/4oz of the cooled Italian meringue and mix using a silicone spatula. Stir in the mango mixture and chill until ready to use.
When the raspberry bavarois is set, add the second disc of génoise sponge and cover with the mango bavarois. Smooth the surface and chill until set.
For the mango jelly, heat the mango purée until it just reaches boiling point. Remove from the heat and cool for 5 minutes.
Squeeze out any excess liquid from the gelatine and stir it into the mango until dissolved.
When the mango bavarois is set, pour the mango jelly on top and chill until set.
When the jelly is set, carefully remove the charlotte russe from the tin and place on a serving plate.
Place any remaining meringue into a piping bag fitted with a large star nozzle. Pipe rosettes of the meringue around the edge of the jelly and top each one with a raspberry. Arrange the mango slices on top of the jelly, starting in the centre and fanning outwards like the spokes of a bicycle wheel. Arrange the remaining raspberries around the bottom of the russe and top with gold leaf, if using.