1. In a saucepan, heat the 15% cream over very low heat. Add the white chocolate pieces, one by one, mixing to ensure a smooth preparation. Remove from heat; add the mango essence. Let it wait.
2. Whip 100ml of cream until it forms firm peaks.
3. Separate the egg whites and yolks. Beat the egg whites until stiff.
4. Gently incorporate half of the whipped cream and half of the egg whites into the melted white chocolate. Reserve in the refrigerator.
5. Place the dark chocolate in a bowl; melt in a double boiler. Add the egg yolks to the melted dark chocolate and whip until smooth.
6. Incorporate, using a spatula, the remaining whipped cream and the remaining egg whites, gently to retain the mousse texture.
7. Remove the white chocolate and mango cream from the refrigerator.
8. Divide the two preparations into small individual cups. Refrigerate for 2 hours before serving.