In large bowl over a bain marie, whisk the egg yolks with the sugar using an electric whisk until the mixture begins to thicken
Stir in the flour and melted butter, mix with the electric whisk
Remove the bowl from the bain marie

Whisk the egg whites until they form peaks and gently fold into the batter, then mix with a large spoon
Preheat the oven to 180°C

Line a 30x40cm baking sheet with baking parchment
Spread the mixture over the baking sheet and smooth with a spatula
Bake for 10 to 12 minutes
Leave to cool on another baking sheet, and cover with a damp tea towel

In a saucepan, mix the egg yolks with 70g of sugar using a whisk
Add the corn starch and mix together
Pour in the lime juice and cook on a low heat, stirring constantly until the mixture thickens
Add the lime zest and the gelatine and mix
Add the mascarpone to the lemon cream and mix together

Whisk the egg whites until they form peaks using an electric whisk then incorporate the rest of the sugar, continuing to whisk
Gently fold in the mascarpone/lemon cream and mix with a large spoon

Peel and then cut the mango into small cubes
Remove the sponge from the baking tray and lay flat on a large piece of cling film
Using a spatula, spread with a layer of Nutella, and then add a layer of lemon cream
Sprinkle over the mango chunks

Carefully roll up the sponge
Wrap in the cling film and leave to rest
Remove the film and cut off both ends of the rolled-up sponge
Using a piping bag, make little peaks of Nutella
Add the mango cubes
Sprinkle with coconut shavings

Chill until ready to serve.