Beat the egg whites, add the sugar (1) and beat until stiff, adding the red colouring and finally the xanthan gum combined with the sugar (2).
Fold in the yolks using a spatula followed by the sifted together flour and cocoa.
Make the ladyfingers. Using a plain 13-mm tip, pipe out onto sheets of baking paper: 50 9-cm long ladyfingers, 3 Ø12-cm circles and 3 Ø9-cm circles. Grate some dark chocolate on the ladyfingers. Bake in a 190°C convection oven for approximately 10 minutes and let cool. Refrigerate overnight.
Cut one of the rounded sides of the ladyfingers. Brush a thin layer of melted dark chocolate onto the flat side of the biscuit discs and brush the other side with the cold syrup. Dip the flat side of the ladyfingers into the syrup and place them on a guitar plastic sheet.
Place the Ø12-cm biscuit discs at the bottom of the Ø16-cm cake rings. Arrange the ladyfingers against the circles (using a Ø12-cm cake circle to tighten them). Pipe 200 g of chocolate mousse into each charlotte then place the Ø9-cm biscuit discs. Finish with another 130 g of chocolate mousse. Close the upper part of the charlotte slightly by pressing down with a rhodoid cone (or by pressing lightly by hand) to create a curved shape on the top. Place in the freezer.
Sprinkle the side of the charlottes with a little icing sugar. Pipe out the decorative ganache between each ladyfinger. Whip the cream and sugar. Fill the center and pipe out rosettes all around the charlotte using a E6 star tip. Decorate with chocolate curls (+/- 40 g).