Grate the rind of 3 limes after washing carefully. Squeeze the limes, keep the fourth for the decoration. Mix together the egg yolks and the sugar until the sugar melts, add the grated rind and the juice of the 3 limes. Thicken the mixture over a low heat, as in the case of custard, stirring continuously and not allowing to boil. Filter this custard. Work the butter into a paste, add to the still hot custard, beat with a whisk. Beat the egg whites until stiff. Delicately fold into the custard with a spatula. Cover the bottom and the sides of a Charlotte mold with the sponge fingers. Fill alternately with layers of mousse and layers of sponge fingers. End up with a layer of mousse. Chill for 12 hours. Turn out on the serving dish. Decorate with the finely sliced fourth lime.
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4 limes
3 eggs
1 1/4 cups fine granulated sugar
1/2 cup butter
40 sponge fingers
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30
mn
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10
mn
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If the sponge fingers are too dry, moisten them with lime juice, 7 tablespoons of water and 1 3/4 ounces of sugar.
