Difficulty:[usr 3]
Prepare the biscuit:grate the zest of the oranges. Put it in a saucepan with 20 g of sugar and 20 cl of water.
Bring to a boil and cook for 15 minutes, drain.
Break the eggs, separating the whites from the yolks until the mixture is smooth and flows into a ribbon, incorporate the zest, flour and cornstarch, whisking constantly.
Preheat the oven to th 6 (180°C).
Beat the egg whites very stiff and gently fold them into the previous preparation.
Butter a cake tin and pour the batter into it. It should not exceed 2/3 of the mould.
Put in the oven for 30 to 40 minutes.
Check for doneness by inserting the blade of a knife. It should come out clean.
Meanwhile, prepare the filling:cut the butter into small pieces and squeeze the oranges.
Then beat the eggs into an omelette in a large bowl. Add butter and orange juice.
Put the bowl on a double boiler and whisk gently until the batter is smooth and thickened (about 30 minutes). Leave to cool.
Take the cake out of the oven. Turn it out and let it cool on a wire rack. Cut it in half horizontally. Generously spread the lower part with orange cream, rest the upper part to reconstitute it
Prepare the icing:put the egg whites in a bowl and gradually add the icing sugar, mixing with a spatula.
When the mixture is smooth and creamy, put it in a bain-marie and add a few drops of lemon juice, stirring constantly. As soon as the icing begins to thicken, remove it from the heat and coat the cake with it using a spatula. Leave to cool.
Decorate the cake with thin slices of orange and candied zest.
