Preheat the oven to 160 °C. Line the base of each spring form with baking paper and grease the edges.
To make the batter, place the eggs, caster sugar and the vanilla extract in an oven-proof bowl. Place the bowl over a pan with a layer of boiling water (au bain-marie). Do not let the bowl touch the water! Beat the batter with the mixer in approx. 5 mins. until pale yellow and airy. Continue to beat the eggs until the sugar crystals have completely dissolved.
Remove the bowl from the heat and beat for another few minutes. Sieve the flour with a pinch of salt above the batter. Fold through as lightly as possible. Add a drop of food colouring to create an attractive pink batter. Divide the batter evenly over the three springforms (use a scale if you want three precisely equal quantities). Bake the cakes in the middle of the oven for about 20 minutes until golden brown and cooked. The cakes are ready when you gently press the top and it springs back. Leave the cakes on a wire rack for 1 hour to cool.
Whip the cream with the mixer until stiff. Squeeze the lime. Beat the MonChou with the icing sugar, lime juice and a few drops of pink food colouring to create a smooth cream. Fold the whipped cream through this mixture as lightly as possible.
Slice the dragon fruit in half lengthwise. Scoop the flesh out of the skin with a spoon. Purée half of the flesh with the hand blender until smooth. Add the dragon fruit purée to the cream mixture. Transfer the cream into the piping bag.
Place one cake layer on a plate. Cover with a layer of dragon fruit cream. Place a second cake on top and cover with another layer of cream. Top with the third cake. Pipe nice rosettes of cream onto the top of the cake.
Cut the rest of the dragon fruit into slices of approx. 8 mm. Use the cutter to create different shapes from the flesh. Or halve the dragon fruit lengthwise and use the melon baller to scoop out little balls. Or do both. Decorate the cake with the balls, shapes, the rosemary and the meringues.
Tip: This is also a perfect Valentine's cake. Make heart shapes from the dragon fruit and leave out the rosemary. Instead decorate with little sugar hearts!
